Slightly OT, but linked, was a thought I was having only yesterday wrt twitter, monetisation and amazon. Personally, I would like a simple, one click way of tweeting amazon recommendations to my twitter followers (who are much more proactive and immediate than my blog readers) with my affiliate code connected to it. This of course opens the same can of worms which you go into above, and it's slightly harder to 'fully disclose' in 140 characters...