Learning Spots, like any other form of communication, are useless without learners, viewers, or readers.
Here is a list of 311 SEO Tools, Social Bookmarking Sites, Social News Sites, Social Networking Sites & Social Media Sites that was put together by Brendan Picha, a Search Engine Optimization and Marketing Consultant.
...and if that doesn't intrigue you enough, the same guy produced a listing of 122 Social Media sites listed by page rank.
Want to find out where your name is available? NameChk takes it one step further and lets you verify the name on 122 social media sites.