I have heard that Kindle will soon allow you to "loan" books to friends with Kindles. That is the only feature the Nook has that the Kindle doesn't.
My hubby has the Sony E-Reader... the major drawback is that he cannot read Nook or Kindle formats. However, it can read PDFs, .doc, and .lit quite easily. Which is good because I have over 10K books in .lit form that I have to reformat to .mobi to read on my Kindle and sometimes that conversion does not make it easy to read.
Knitting to keep my sanity. It's working... kinda...
OTN: Dr Watson's Cable Crew Neck
OTN: Writer's Cardigan