I really enjoy using Slicehost. You get a whole lot of server for very little money. The trade-off is that unlike many other VPS's you must set up the entire server yourself from scratch through the command line. This can be a little frustrating the first week, but VERY rewarding in that you learn the intricacies of server setup in the process (assuming you don't already have that capability).

Even more importantly though, they have excellent support. Forums, wikis, and live chat through their site. I remember getting help one time when I was first starting out, chatting with one of the owners at 3am on a Tuesday night as he helped me work out a bug with my server.

Very happy with slicehost. Great latency, too.