How do you level your turntable?

Short of buying a 400 dollar digital level, what have you found that really does the trick. I've tried various cheap bubble levels with fair to poor results.
"Cheap" bubble levels are adequate. Why do you feel the need to go more high-tech? Does your table sound bad?
I really think that a quality TT really needs to be leveled to the point of absolute perfection. I would agree that owners of linear trackers need to pay more attention. I think your problem is your table and where it sits.
Lindisfrane, nope, turntable sounds fine :O) I have a new protractor and just thought I'd try for a "best of my ability" setup. I'm sure some of us are pretty anal about leveling and thought I'd tap in.

Schipo, My table is set up on a spiked, heavy wooden audio stand with granite inlay. Unfortunately using a pier and beam floor, but I'm not ready for a wall mount yet.
I use a bubble level to good effect.
I've got a marble slab on top of an inflatable tube. But...
I level the stand first.
Then I put the table on top of the bladder / slab combo.
Then I put the bubble level on the bare platter. I put it at several places along the arc of the tonearm, where the cartridge would read
Then I move the air bladder under the slab a little bit at a time until the bubble level reads level. The slab isn't necessarly level, and the plinth isn't necessarily level. But the platter is.
Every couple of months I add more air and repeat the last step.
Thats just me though.
An excellent bubble level on this site: ( Proper leveling(of the platter) is absolutely essential for good reproduction via vinyl.
Bubble level from hardware store - $3.79.
Rodman99999 Yep, both offered here look like winners. Thanks.
I use a bubble level and a Sears digital level that cost about $25. I guess I am as anal as most of the audiophiles here.
I use a 12" carpenter's "torpedo" level.

Ya gotta level your platter to the best of your ability. When mine was off about 1/3 bubble, I was getting the weirdest phase anomalies and balance problems. On one mono album, the sound seemed to come from from the front window to my left--90 degrees left of the point between the speakers.

Using my trusty Sears Craftsman level to get the bubbles to level longitudinally, laterally, and diagonally fixed all this.
I have a linear TT (LT-30) and am another who uses the Sears $25 digital laser level.
1. Level stand
2. Check TT from platter and base
3. Sit back and enjoy, and do not check again unless I need to
any good bubble level is fine.
I used several long levels (two 4' and one 2') to check the accuracy of three 12" ones. (One of those was actually out a little.) The accurate ones are used to level the platter. Once that is done, I permanently mount a pair of custom made glass vials into the plinths of my turntables, so the user can keep an eye on it all along. To me, levelness is a big deal.
Great input really got me thinking. I had forgotten that the spindle of my turntable is removable. With it out I was able to put the bullseye bubble level directly in the center of the platter. That gave me a reasonably good reading. Guess I'm headed to Sears now.
I use a cheap, 1" long bubble level (not a round one, which would be pretty useless).

To compensate for the inaccuracies of a bubble level, if any, all you have to do is spin it 180 degrees and re-check on the same axis. If the results differ, halve the difference and you're level. Nothing could be simpler.
I picking up a pair of cables at a fellow A'goner's house a couple of weeks ago and he showed me an interesting experiment relating to bubble levels. He showed me 4 bubble levels on the same surface, each of which had a different reading. He explained that these are all hand calibrated using some sort of photographic device, which explains for the discrepancies between the bubble levels. He said he uses a digital level for his turntable, which is the best way to achieve a perfectly leveled table. FWIW, he's an architect and an engineering professor at a major university.

Me, I use a bubble level because I'm feeling cheap.
Dougdeacon has the answer to this. I have $500- worth of levels to install fine cabinetry and I always rotate 180 degrees and halve to find dead nuts. The ONLY way to find true level with a bubble.
Ditto Doug/Zen
A 9" "torpedo" bubble level works great. $4-5 dollars at Lowes or Home depo. A torpedo level gives you a north-south, east-west and diagonal level reading at the same time.
Actually, a 9' torpedo oughta level things very well. ;-)
I use digital level with great result. You can actually level to zero degree with digital level. It only gives approximate indication (hardly to zero) with bubble level. You hear the difference when you level your platter to zero degree.
I use a bubble level on the plinth, not the platter.
The plinth is not necessarily in line with the platter unless you have confirmed that it is.
Just a newbie and still working on setting my my first (real) turntable, I thought I would just put in my $0.02. Being a carpenter with extensive experience with levels, I just wanted to point out the proper use of a bubble level. Although it looks pretty simple and straight forward, it is very important that you read it correctly. Most levels have a bubble that is smaller than the lines it is to be centered in. Just because the bubble is "inside the lines", that does not mean it is level. The bubble must have EXACT spacing from the edge of the bubble to the corresponding line otherwise it will not be level. I have also seen levels where the bubble is wider than the two lines. Here you need to be sure the overhanging bubble is equally hanging over the lines. In either case, you will be surprised as to how much out of level your turntable will be if this proceedure is not followed. From all that I have been reading on setting up a turntable, it seems that this step it very important for good results.
Pisa tower .. Markpao? :-)
I use a good carpenter level too with two lines and the bubble not overhanging
A bubble level should work fine. You might want to take multiple measurements near each corner though.
I use the plinth because that's what the arm is mounted on, not the platter. Might not be the right train of thought, but it makes sense to me to level the surface that the arm is on. Example, say the platter is different from the plinth by a degree. Well, if you level the platter, now the plinth is off, and so is the arm. This could cause the arm to want to swing because it's off.
Markpao- Being a carpenter- you should know that you must turn any bubble 180 degrees to confirm level. I have to send my Stabila levels to Germany every year or 2 to be dialed in. They are ALWAYS off a bit -
I also use just a bubble level on the plinth, and double-check it on the platter.
I have a few bubble levels
My smallest one has a magnet at the end is the mangnet bad when levelling your tt
buy some level of just a vial that has clear precision specs from manufacturer, usually from Japan, Europe, USA, Canada
Level the turntable, not the plinth. Ideally the tonearm headshell and turntable should be level.

good point, but, actually, ideally you want to level both the arm and the platter, neither of which might be aligned with the plinth.
Piedpiper's right.
1. Level the TT stand
2. Level the platter top surface
3. Adjust the tonearm mounting so that its bearings are level. This is easier on some arms than others of course.

Levelling the headshell is a good place to start, but whether it should remain level varies with the cartridge. Nearly all cartridges benefit from fine tuning of both azimuth and VTA, which could result in a non-level headshell, depending on the rig.
As others have posted, I also like to use a 9" torpedo level. I like to think I'm getting a better idea of the general level-ness of the platter. My Galibier doesn't have this issue but I've had tables in the past where the platters are not flat. Some either had a convex or concave surface. This can be dealt with but it is much easier to do so when you know this condition exists before trying to level.

Many levels can also be checked for accuracy by flipping them over as opposed to turning 180. Either way gives the same indication of how accurate the level is.
I used a small, straight level, not a bubble level. You need to measure in all directions - back-front, side-side, and both diagonals.

First on the table, then on the plinth, then on the platter (just spin it slightly to get all angles).

A nice feature of the servo'd arm of my Sony PS X800 is that it does not need to be leveled. If you could find a way to keep the platter and the LP in place, it would work upside down!!