Limit Post Revisions

Hello,
I am running a website for a local community blog. It currently has about 350 blog posts, and that number is steadily rising with community activity, which is great. The thing is, i’m seeing that there are tons of post revisions, and I can imaging with so many posts, with many yet to come, that they can really use up space on the database. What is the best way of dealing with this?

thanks
Zach