How much do you want to spend?
@ebookrights: It depends on your budget. If all you want to do is read ebooks and don't need great battery life then there are low-priced LCD screen readers that don't have many features, price is around $100 and there are many to pick from.
If you want to spend more it then depends on your needs. For a simple and easy-to-use book reader with a color screen, the ColorNook at $250 is a good deal. It's bug-free and user-friendly but a bit heavier than I like at almost one pound. That doesn't seem like much until you've held it in reading position for an hour or so. It runs Android but right now the Barnes & Noble user interface keeps you from using that OS without a hack. The Archos 70 is slimmer, narrower and lighter than the ColorNook and costs about $50 more for the 8 gig version. It's easy to access the market but it's not directly supported by Archos, instead they offer an appslib (android app library) of apps they've tested and work on the device.
You might want to watch eBay too as many who bought the latest device a few months ago are now dumping them to get the newer models. If you only want it for reading then an e-ink device might be better unless you want the backlighting on a color screen. They're pretty cheap now, too, and very reliable.