Zootool ‘lassos’ not only images, but documents (like PDFs), videos, and pages (not complete pages yet) and stores them in your ‘zoo’. Content can be organised into ‘packs’ (folders) and as you would expect, it stores the original URL, and offers fields to change the title, and add tags or a description. It also provides integration with services like Twitter, Tumblr and Facebook, along with short urls, for sharing what you’ve found.
So, rather than having favourites being stored on different sites like Delicious, Vimeo, YouTube etc, they’re all in one place. In some ways I think of it as a huffduffer for anything that isn’t audio.
Interesting web application. Not sure I’ll use it, but you might want to check it out; here’s my profile.
The thing that’s really missing for me (and not trivial to add) is to capture a site as a whole screenshot — that would make it perfect for a scrapbook of visual inspiration.