Dropmark is a great service for sharing and collaborating on media, files, and links. It’s kind of like a cross between CloudApp and Dropbox.
The company has a simple tip that makes it easy to plug an RSS feed for any of your Dropmark collections, even a private one that requires you to login with a password, into iPhoto. This opens up a lot of possibilities, such as backing up your photo-heavy Dropmark collections to making it much easier to use shots from your collaborative photo albums in other Mac apps.