prgmr.com is very good VPS service which offer good value for money if you are comfortable with command line. In my two years experience with them i had occasional outage. Over all very satisfactory.
Now i m planning to move over to hetzner.de and buy their EX service root server. I hope to utilize my VPS experience to install a Xen Server 5.6 Sp2 on it. Then may be install couple of bunch of VMs to do testing and Dev machines for the consultants,