Open source cloud virtual server software

I love PuTTY !

The PuTTY executables and source code are distributed under the MIT licence, which is similar in effect to the BSD licence. (This licence is Open Source certified and complies with the Debian Free Software Guidelines.)

In the long term EC2 is rarely more cost effective than dedicated servers of your own. It's main advantage is in rapid scalability. If you have a relatively slow changing userbase then it is probably not worth it.

But the great thing is that it is easy to set something up and try it out for just a handful of $, without having to lay out a lot on hardware in advance.

There are ready made AMIs for Glassfish. My advice would be to try out 1 or 2 small instances, it'll show you clearly if VPS/Dedicated servers will be better value and give you a much better idea of your requirements.