A few years ago, I created a community on LiveJournal called A World of Scribbles. My desire was to design a place where people could share their writing, participate in friendly competitions to develop their writing skills, and perhaps most importantly, receive feedback towards that end. The community's been through a few iterations, but I've recently started it up again.
With that brief introduction, I invite you to stop by and take a look at worldofscribble. There's a biweekly competition based around a writing challenge, and two recurring features, one on timed writing, and another that's completely random. There are discussion threads for people wanting to brainstorm on the assigned topics, followed by a vote to determine whose entries were the best. In short, if you enjoy competitive writing, as well as discussing how to write well, this is the place for you.