Colo Provider That Handles DDoS Attacks

One of the sites I run is a forum with a political component, and 4-5 times over the last week we've been seeing DoS attacks. They're not terribly sophisticated -- generally 1-3 compromised servers throwing packets my way -- but they're enough to clog my pipes and take my sites down.

What I'd like to do is put a new server up at a data center that's D(D)oS aware that can hopefully respond to these attacks automatically. My current provider has been giving solid support, but the best they can do is null route the affected IP, rather than filtering the incoming attack.

Can y'all name a few providers I should look into? Right now I'm just looking to move 1 box (or maybe a box and a firewall depending on the setup).