1 or 2GB disk space, 10-20GB transfer, 20+ domains, Helm, POP and SMTP email services, etc etc etc.
An integrated billing system, or hooks to create it would be a huge plus. So would SharePoint Team Services.
I'm not at all interested in dirt cheap oversold unlimited services.
Reliability, speed, service, and provider's company stability are infinitely more important to me than saving a few bucks a month. I can't stress that enough. I will absolutely be moving to another hosting company in a flash if the new provider can't deliver those things, so please don't waste both of our time.
I'm moving some domains from a hosting company I've used exclusively for about seven years. Their service really slipped badly recently, so I'm moving all the domains off their servers. If the new provider takes good care of my and my clients for a fair price, I'll be with them for the next seven.
I don't know how attached you are to the Helm control panel but you may want to consider www.fluidhosting.com if you are willing to try H-Sphere. They have all your other desired features (most hosts will). They are located in an Internap datacenter and from what I've read they use quality hardware so reliability should be excellent.
Your best bet however is to try to use the Host Quote feature at the top of the site and have hosting companies that can accomodate your criteria contact you as webhosting companies are not allowed to advertise in this forum.