What the heck is bias anyway?

Here's the classic simplified answer: Bias is to an amplifier what the engine idle speed adjustment is to a car. Set too low, there are performance issues. Set too high, and many cars and amplifiers also have performance issues, and additionally pay a price in efficiency and component life.

Now I'm admittedly somebody who has a penchant for verbose technical ramblings . . . but really, was it that difficult to answer the OP's question?

I dunno Trelja, I'm going to have to stick by it. Amplifiers and and cars are certainly different, but the main, general pragmatic, neophyte-level points between bias adjustment and idle throttle angle correlate well:
- They both determine the level of energy dissipated by the system while it's performing no work, but in an active state waiting to be used
- The proper setting is one that is neither too high nor too low, depending on the machine's design and intended application
- A misadjustment of either rarely results in a catastrophic condition, but results in reduced performance and/or increased stress on the system
- Both are traditionally adjusted by turning a little doo-hickey with a screwdriver, in a manner hidden from the casual end-user
- A similar level of mechanical/electrical aptitude and tools are required to adjust either to a factory-specified setting
- Deviation from the "stock" setting is ill-advised, unless you have the technical competence to evaluate the many interrelated system parameters

Above all, I think this analogy gives a good insight to one who is unfamiliar, whether it's something he/she should be comfortable twiddling with.