Advanced Internet Technologies (AIT) is currently running a great offer on dedicated servers. I checked the total I was paying for Windows shared hosting accounts I had scattered across a few hosts, did the math, and decided to move to a dedicated server. The promotional price for lower-end dedicated servers is in the "too good to be true" range but the machine has performed better than I expected. 8 IP addresses, 2.4GHz Celeron, 40GB HDD, 256MB RAM (the only drawback I've seen), Windows 2003 Standard, and full control via TS/RDC. They even put a "don't forget to leave the remote admin port open when you install a firewall" ReadMe.doc in the startup folder (I imagine they've received a few calls from people who forgot that, I know I've done that before on my local network). The network (usually the biggest bottleneck on the shared hosting sites I've worked on) has been more than fast enough for the sites I am developing there and the speedtests I've run have been higher than any I've seen from other servers I've used (although running via remote desktop always skews the results) and definitely higher than my cable connection here. I have the bottom-end server but there are at least 4 better plans to choose from if you're looking for more power and/or space. I can't vouch for their shared hosting but they have some amazing promotions on shared hosting prices at the moment, too (3GB of space for under $20).
[UPDATE: I just received a phone call from AIT and was able to voice my concerns regarding the problems I had during the initial setup of my account and have been assured that the problems I had are being looked at. I have had no problems at all with the server since it was set up. So, the post has been edited to focus on the technical aspect of the dedicated servers they offer.]