The folks at Flowtown have put together a quick reference guide to six different social media services. Called the SMB Social Media Cheat Sheet, it contains basic stats on Twitter, Facebook, YouTube, Google+, Tumblr and Digg. What, no LinkedIn? That is perhaps the biggest missing service, but otherwise the infographic, reproduced below, is worth bookmarking for those noobs in your company that are looking to learn more about each service.
I particularly liked the how to begin for each service.