Del.icio.us and Flickr. Hell, and Google. I'd say you want something that is spelled like it sounds and, ideally, short. IMO, .com is pretty important too.

Del.icio.us and Flickr. Hell, and Google. I'd say you want something that is spelled like it sounds and, ideally, short. IMO, .com is pretty important too. Bluedot.us (a Seattle startup that's kinda in the social bookmarking space-- about 1.5m uniques last time I checked) switched over to Faves.com in December. I checked Alexa, but it doesn't show data for the old URL. Might be interesting data if compete.com or someone else has it handy.