An un-metered plan means that there is a limit set for the amount of outgoing traffic that can leave your server. With a 768kb/s limit you will be able to upload approximately 100kB/s to your users, with a 1.5 megabit limit this would be 200kB/s. A typical DSL user will have between 128kb/s-3mb/s.
Unless your streaming heavy audio/video this is great bandwidth for a VPS server. Your provider should have ample connectivity to the internet, and likely will dedicate this slot of bandwidth to you. There is no monthly billling for bandwidth because you can not use more than your server is set to. A 1.5 megabit connection can pump out approximately 500gb on a monthly basis.
rackforce offers unmetered vps at 1.5 mbps, 3mbps, 5mbps, 10mbps
spry also offers unmetered vps at 1.5 mbps
jvds offers unmetered vps at 3mbps
fdc also offers unmetered vps at 100mbps
pricing and support varies. do a search for specific hosts.
rackforce support is not bad. I had used them.
I had a colo at fdc and only occassionally had problems with speed. I was on their 100Mbit shared plan and could easily push 4Mbit out from it. Others seemed to have problems. But I could only complain about the latency. I had some other issues as well and I am leaving fdc because I am trying to run a game server and I think their transit must be too saturated. But if I was running a regular webserver I might have stayed at fdc. I could push alot. I think I once pushed 30Mbit out of the server. Never any high sustained bandwidth usage. But I have seen graphs of other people pushing 25Mbit sustained.
Forgot I was on the vps forum. I wouldnt go with their vps offerings. Seems like alot of complaints in their forums about the vps output. www.fdcservers.net/vbulletin