Do you love hacking on APIs? Are you tired of your address book contacts being out of date? If so, we’ve teamed up with our friends over at Rainmaker to introduce the Rainmaker API Challenge. The Rainmaker API Challenge is a month-long (well, now it’s a half-month:) contest where developers can win part of a $30,000 prize package which includes $2500 cash, an iPad2, and some free SendGrid credit! The rules are simple: Build something incredible using the Rainmaker API and submit it to the contest by June 30, 2011. I realize you only have two weeks left, so get on it this weekend! Dive into the Rainmaker API Challenge and get started!