Signing up for Amazon EC2 now for an inexpensive VPS-like solution, where I can tinker with a live web server for which I have root access and can install and configure whatever I want. I also considered Rackspace Cloud Servers, but though they may be a bit faster, they’re a bit more pricey for my needs. My instance will only be up when I want to toy with it (maybe 10 or 20 hours/month?). I don’t plan on having a running website/app there for a little while and I don’t want to pay for all the time that it’s up and running and no one is using it.
Some resources for comparing Amazon EC2 vs Rackspace Cloud Servers:
http://www.rackspacecloud.com/cloud_hosting_products/servers/compare
http://www.tonycode.com/blog/archives/122
http://blog.schicks.net/2009/rackspace-vs-amazon/