I recently got a B&N Nook Color from a friend, which has been rooted and turned into an Android tablet. I'm pretty happy with it so far, and I've just loaded it up with a bunch of gaming PDFs.
RepliGo for PDF reading at the moment, and it works pretty well and reliably, but it does have one major fault (for my purposes), which is that it will only keep one file open at a time. I believe that something called GoodReader for iOS uses a tabbed interface to switch between open files, but I haven't been able to find anything comparable for Android. Does anybody out there know of such a thing?
Being unable to switch easily and seamlessly between files makes tablet-based reference reading much, much less useful or easy than it should be. I really hope they'll be addressing this soon.