searching for high bandwidth

Thank you to everyone that responded to my low-latency bandwidth question, and please if anyone else has a suggestion along that line please do respond to my last email! I'll compile the responses I get and post to the list in a few days.

Anyway, I'm emailing now to request any information on sources that would help in searching for high bandwidth (meaning T3 or similar) providers. I already know about (a affiliate) and through Google found, but what else is there? How do you all figure out who to contact when shopping around for additional bandwidth?

I'm searching for a provider in the Washington, D.C. area by the way, and currently our fractional T3 is provided by UUNet. I will of course be contacting them, also I've already contact Cogent based on someone's suggestion yesterday or the day before.