I love my Studio 14z, and I see that the base model is down to $599 (possibly because they're getting ready to introduce a model with the new Core i5/i7 processor?). You could probably do even better than that if you're willing/able to wait for a coupon good on a refurb from Dell Outlet.
The key features for me are the optional backlit keyboard (IMO, the best $25 upgrade ever!), fast Core 2 Duo processor, battery life (I can get about 6 hours out of the 8 cell battery with normal Internet/word processing use; I'm sure it would be less when gaming or watching a lot of video), HDMI, and high-quality speakers.
My friend just picked up a new 14" Toshiba Satellite from Best Buy (one of their Blue Label deals), and I have to admit it's pretty sweet too. Unfortunately, it's out of your price range unless it goes on sale (current price is $899). It has the new i5 processor and comes with Intel Wireless Display, which is really nice.
ETA: My brother's Sony Vaio SR590 seems nice too, but I haven't really spent much time with it. Also, I'm pretty sure that would be above your price range too (Sony's website lists the SR series as starting at $939).