I just found another cool site today - Zimmertwins! So I spent some time playing ... check out my movie by clicking on the picture. (Please excuse my shameless self-promotion) ;)
Although you can make a movie for free, I bought a one-month membership for less than $4.00. The site advertises 50% off the membership costs if buying for a classroom.
I think this would be so much fun in the classroom - talk about motivating students to write! It's also great for differentiation, because there are ready-made movie starters for those students who have difficulty choosing a topic or getting started.
I think I'll do this with my students during our media unit. I also think I'll pair it with teaching dialogue, and have students use proper punctuation with quotation marks in the speech bubbles. Students would have so much fun sharing their videos over a large screen - you could even turn it into a "movie premiere party" complete with popcorn. When students finish making their movies, they can email the link to you for assessment, and they can even email it to their parents to share what they've been doing in class. SO.MUCH.FUN!