I expected quite a few documentaries surrounding the theme of the 'internet' and a few fictions but I haven't seen that many about this theme, or at least I can't recall that many. Films like 'Hard Candy' has the theme running through the film as this is how the characters meet and is eventually the downfall of one. But I thought I'd go with...
The Fifth Estate
The Social Network
Don't forget to check out what Wandering Through the Shelves picked, the blog that started Thursday Movie Picks.