Google Bookmarks now lets you create and share lists
They're actually quite useful! On top of creating and sharing, you can import all of the bookmarks from a friend's list (or a public list) into your own Google Bookmarks account. You can also open up lists to let your friends, or the public, add new links to them. Since this is a Google product, I don't think you'll be surprised to hear that it also suggests links that might fit into a list you're making.
Bookmarks are in a weird place right now. Sites like Delicious, which looked like the future of bookmarking a few years ago, have become less relevant. Many people are storing their bookmarks locally, and syncing them across machines with plugins like Xmarks or features like Chrome's bookmark sync. If anyone can bring users back to web-based bookmarking, though, it's Google, and a lists feature is an important start.