Yesterday I met Jake and Brian from Toobla. Toobla is a brand new social bookmarking tool and I was very impressed!
As Toobla describes itself, “Toobla lets you easily collect, enjoy and share visual bookmarks to websites and other embeddable content (i.e. widgets like YouTube or other videos, photos, documents, games and widget applications).
Content of any kind can be collected into online folders that users can then easily share with friends via Twitter, Facebook, email or elsewhere on the social web.
Users can also create their own mashups of their favorite content, putting multiple things into a single widget which they can post to their blog, MySpace, Facebook or any site online.
Frequent users of the social web can have their content automatically sent to Toobla so that anything they bookmark or favorite while they find content online ends up on Toobla, thereby helping them to better organize and never forget where to find their favorite content online.”
I highly recommend that you visit their site to see how you can harness social bookmarking for your agency.
NCE Social Media 
You should check out a better sharing site than toobla, dropstr.com. It does a lot more than what toobla does, pretty neat.
Chris, thanks for pointing out dropstr.com. It is my opinion that Toobla is more dynamic and easier to use than dropstr. Also based on the brief tour you get visiting dropstr’s site, it doesn’t look like it does more than Toobla.
However, not every tool is best suited to everyone’s needs. So dropstr may be more helpful to others. But at least check out Toobla.