Most movies on general release or between 80 and 120 minutes.
Really, really long: 187 minutes. Just over 3 hours.
diary of a wimpy kid
Well, you can rent it from Netflix. I know they definitely have it, because I just added it to my Queue. I'm not sure if that's what you were looking for, or if you wanted a website to watch it on.
Until October 1st, so hurry and see it!