What should I use for my startups GeoDNS provider?

I run a startup that is starting to really scale and we're looking to distribute our infrastructure internationally. I'd like users to be routed to the closest servers to them geographically, and I'm thinking that DNS is the best way to do this.

I had Zerigo recommended to me for their DNS service - but I wanted to see what else is out there that can provide this sort of service.

What do all the rest of you use for your DNS service? Does anyone have experience with GeoDNS?