That is an understatement. Doug Cornelius, Chief Compliance Officer at Beacon Capital Partners, has collected 144 of them, and it appears he adds new ones as he finds them. If you need a sample, check this out: Social Media Policies Database.
Hat tip to Tom Mighell, whose Internet Legal Research Weekly, is another great resource and a must week-end read for me. For information check out his blog, Inter Alia.