Good sound possible on a bookshelf?

Are there any high quality bookshelf speakers whose sound is not significantly degraded when placed on a bookshelf? Because of layout issues, I don't have space in my new living room for floorstanding speakers or monitors on stands (there is a far corner that could take a subwoofer). But I do plan to build a 20-inch deep cabinet surrounding the fireplace and TV that could also house equipment and support speakers. Budget range: from Axioms or Polk LSi9s to Revels. Thanks for all comments.
There are speakers specifically designed to be used against the wall, so for those speakers this set up is not a terrible compromise. I have seen them in different places, but don't recall what brand or model they were. A little homework will reap rewards (sound like a fortune cookie) since, the truth is out there. The budget you mentioned should not be a problem.
I own a pair of Von Schweikert VR-1's that I have on stands but have read that they perform well on a bookshelf as well. You can get some additional information from their website at the Von Schweikert site.

I've also owned the Polks you mentioned and I would forwarn you that I would imagine that the bass response from those would be overwhelming if put on a bookshelf. The VR-1's are much better and even-tempered speakers than the Polks in my opinion.

The one thing to keep in mind about the Von Schweikert's is that they take 100+ hours to break in and the change is dramatic. If you pick some up be prepared for the agony of the first 100 or so hours - but, man, do they sweeten up from there on out!
Hi - I got good results with a pair of B&W Matrix 1 (bookshelf model) and a good friend of mine has Aerial 5 in his office and getting nice results.

Hope this helps,

Allison is making a come back I believe, they are a brand name from Ancient Times B.C. (Before Cable)

They were specifically designed to be placed on a bookshelf and up against the wall. I thought I saw something about them at the show in NYC.

If Kr4 is around, he will know whats up.
I know ACI makes versions of their speakers with the crossovers tweaked for being in a bookcase. I think Salk Sounds may too.
North Creek has one or two designs that are specifically intended for bookshelf or near-wall placement.
I really have found sealed speakers to work much better then ported when placed near a rear wall. Front ported speakers might work as well.

Still ported or not any speaker I've owned does have a deeper more layered soundstage when moved away from the wall, ported and sealed.
Disclaimer becuase I sell them, but the Joseph Audio RM7Si MKII's, as they are front ported work great on bookshelves.
I'm using a pair of Tyler Reference Monitors on shelves and these front ported speakers image amazingly well and sound great.

While they may sound even better on stands, they're great on bookshelves too.
Yes,but Compromising.
Revel M20 good choice.Flush mount setting at back of speaker.Not to fussy with positioning .Good idea to give few inches at back to breath.Supplied with shelfmount feet as standard.Remember grilles extra.Well balanced speaker .Not the M22,rather the M20's.
I know this isn't an answear, but have you considered in-walls?
Thanks for all the good, rapid suggestions. The only one menioned that I've actually heard is the Joseph, which I liked a lot. Living in Bellingham, WA with nothing but box stores in the vicinity makes auditioning difficult, but I'll head for Seattle soon and check out some of the others.