The delightfully titled blog, Web Two-Point Whatever has a roundup of social news, networking and bookmarking sites Romlet, Peopleized, Plime and Shoutwire. Like me, you may be a bit Web 2.0-d out at the moment, but as the author says:
"There are...compelling reasons to look at newer beta and/or less well known sites. Some sites provide new services or features, or recombine old ones in unique ways. Others compliment or build on the functions of existing social media or other sites."
4 Up-and-Coming Social News, Networking and Bookmarking Sites You Should Know [Web Two-Point Whatever]