I love Kippt
I've been a Twitter addict for a few years now. The primary reason that I am addicted is that it is my main way of discovering things related to front-end work. Of course, I dig the social part of having tweetversations but the links are my main reason for going.
Kippt has provided the best UI and UX that I have seen for link collectors like myself. It is a gorgeous site and has all of the right features for quickly organizing and discovering links. It is a fantastic design and I love it. So, I'm dedicating extra time each day to build up my collection.