Seven Celebrities Who Should Get on Twitter Right Now

Twitter's all about self-promotion. This we know. MC Hammer knows that, too, and apparently has been quite successful at it, which explains why Gravity Summit invited him to keynote this week's social media conference at Harvard.

For those of you who don't know, Gravity Summit describes itself as a "bridge" between social networking media and business leaders. Basically, it smacks business leaders upside the head and tells them to use Facebook, Twitter and all those other sites to help make money. We're not sure what kind of money MC Hammer makes these days, but he has amassed more than 1.3 million followers on Twitter.

Perhaps it's because of his reality show, perhaps it's because of his camp value — regardless, people are getting regular updates about his happenings. And he knows what that means: there has to be a way "to sell those people something." Indeed.

That's why we've compiled a list of seven famous people from all walks who would be well-advised to get their tweets in gear to sell something, reclaim their formerly glorious profile or simply satisfy our selfish desires.