I just ordered a TweetNotebook. It's a personalized notebook featuring one of your own tweets at the bottom of every page. All you have to do is put in your twitter name and the system (supposedly) picks out your best tweets to line the pages with.
Part of what I like about Twitter is that things you say are momentary, small things go from foreground to background very quickly, very reflective of real life. The other thing I like about Twitter is that it captures moments in time, on an ongoing basis. To me, that is what the TweetNotebook is celebrating. It is kind of like a photo album, reminding you of passing thoughts and captured instants.