Own-Id was down from 2008-01-18 15:16 GMT to 2008-01-19 12:47 GMT. Sorry to everyone for this outage. The reason was that the Java VM ran out of memory. This means that Own-Id probably has a memory leak.
One of the problems was that it took a long time for me to find out that the server was down. I've now set up Montastic to send me an email if the server goes down again, they also provide a web feed of server status. This should mean that if there's another outage, I should know much sooner.
There remains the problem of finding the memory leak. I'll let you know how I get on!