If I can get on my soapbox for a second (and let me know if this isn't cool - I just like pointing people towards more effective products), I'd like to call attention to http://www.lookwork.com , which was designed and developed by Ben & Eric of Svpply fame quite a few years ago using the jQuery Masonry that people seem to think is Pinterest's bread and butter. You can follow friends, tag images, add your own feeds a…
My favorite image bookmarking site today is designspiration. Different strokes. The deck shows the direction we're going. Anyone will be able to create any stream. So, you'll be able to aggregate all of the quality images you want :)
Designspiration thumbnails those images so small, it's impossible to just browse and tag without needing to click into it. That's my main complaint with most if not all of these services; I shouldn't have to click to see it in its full glory, and often times, the details get lost at that size and certain works are inherently at a disadvantage of being seen because of it.