Find out when someone joined Twitter - select some text with an @username and click the bookmarklet. Or just click it when you're looking at someone's profile!
Bookmarklet Source Code:
javascript%3Aq%3D%22%22+%28window.getSelection%3Fwindow.getSelection%28%29%3Adocument.getSelection%3Fdocument.getSelection%28%29%3Adocument.selection.createRange%28%29.text%29%3Bif%28%21q%29%7Bp%3Dlocation.href%3Bx%3Dp.indexOf%28%27http%3A//twitter.com/%27%29%3Bif%28x%21%3D-1%29%7Bq%3Dp.substr%2819%29%3B%7Dif%28%21q%29q%3Dprompt%28%22You%2520didn%27t%2520select%2520any%2520text.%2520%2520Enter%2520a%2520twitter%2520username%3A%22%2C%22%22%29%3B%7Dif%28q%21%3Dnull%29%7Bif%28q.match%28%27@%27%29%29%7Bvar%2520ai%3Dq.indexOf%28%27@%27%29%3Bq%3Dq.substr%28ai+1%29%3Bif%28q.match%28%27%2520%27%29%29%7Bvar%2520si%3Dq.indexOf%28%27%2520%27%29%3Bq%3Dq.substr%280%2Csi%29%3B%7D%7Dlocation%3D%22http%3A//www.whendidyoujointwitter.com/%3Fusername%3D%22+escape%28q%29%7D%3Bvoid%25200
