If you're running a contest using Twitter, and need to randomly select a user to be the winner, then this tip from The Social Hour 170 will save you time and hassle. It's a website called Twitter Draw, and it will simply pick a Twitter user at random. It can pick a random follower of an account, a random retweeter, or it can choose based on a specific hashtag used.
A lot of social media sites like Facebook and Twitter have certain rules for contesting, and they often insist that the winner be chosen at random. It's a lot more convenient than copying and pasting a bunch of user names into a spreadsheet to pick someone. Twitter Draw is free, and can be found at twitterdraw.com.
To hear more about Twitter Draw from Amber MacArthur and Sarah Lane, check out The Social Hour episode 170.