ExceptionalServers.com

Planetmaster's seedbox service is pretty great. Excellent pricing, fantastic service. Definitely go grab one while they're still available. Don't be put off by the website being under construction, the support is solid. I've had no complaints, and I get a snappy 100Mbit up/down consistently.

cutorrent.com

EDIT: It's now CUTorrent; no longer under construction. By "solid" support, I mean under ten minutes for a response at any time of day. They offer 100Mbps, 1Gbps, and 10Gbps. Still the lowest prices I've ever seen. Still using them. Still don't know why anyone would buy a seedbox anywhere else.