We tried out mqrius' server and encountered a few difficulties, but I have no idea what was causing them, so it could just be that OM is a bit shaky.

I poked around a bit more.
Basically, I got "java.lang.OutOfMemoryError: PermGen space", so I figured it was a lack of allocated memory and increased the allocated heap space (Xmx and Xms). However, I did some further googling, and apparently the PermGen space is separate from the heap space. If it goes out of memory, it might be caused by either a normal process, or by a memory leak. It might be solved by having java unload its classes. I'm running it with the following flags at the moment:

-Xmx1024m -Xms128m -Xmn512m -Xss512k -XX:+CMSClassUnloadingEnabled -XX:+UseConcMarkSweepGC -XX:MaxPermSize=128m

Since I now applied a fix that might be specific to the problem, it warrants giving it another test.

But honestly, ideally, I should not be the one to test OpenMeetings: I don't have enough knowledge to judge if I'm doing things wrong or if OpenMeetings is. The "fixes" I try are just suggested by random googling, not by careful consideration.