The version of QuickOffice installed on the Nook is licensed by B&N as the reader only. It's an ad-free copy of the free version available in the Market. (I'm not sure if free QuickOffice in the Market has ads, actually)
Documents to Go and QuickOffice are the main office productivity suites for Android from what I could tell. Both required the paid version to edit Office documents. I have Documents to Go. Word and Excel support are quite good. PPT is not quite up to snuff. Unfortunately, trials are only 15 minutes now, but if you load some files onto your card that you want to test, it's just barely enough to scroll through quickly and try a couple features.