I have a small virtual server at slice host (256M). I originally thought it would be appropriate for rails/mongrel and apache, but probably too small for a java web container. But, after installing resin and running it through some basic tests, it looks like even the small slice is fine for testing and semi-live (e.g. demo) applications.
My next step is to test jetty and glassfish. I don't think there will be problems with jetty, but glassfish may be too much of a memory hog to work correctly.
Running 'top' shows that resin actually uses about 60M when it starts up and goes up to 90M under basic use. This will undoubtedly change when spring/hibernate and real database access kicks in, but it looks good so far. My goal is to install a grails application to see if slice host can be used for basic demo purposes.