I suppose the laziest way to describe deadtre.es is as 'del.icio.us for books'. I've been tinkering with it on and off over the last couple of months or so, and thought it time I polished off the roughest edges and gave it a mini-launch here. As far as functionality goes it's missing some fairly obvious stuff at the minute, but it's usable and includes a bookmarklet for adding books from the pages of Amazon and a simple JSON feed should you want to display your reading list on your blog. If you want something a little more comprehensive you might want to check out Library Thing, BookJetty or maybe Amazon Wish Lists, but if you want a super simple way to keep and share a reading list you're more than welcome to give deadtre.es a go.
