In all honesty the stuff generated by this so far seems to be more compelling than most online jam theme generators!
I've used a lot and don't often tend to get much from them but this is cool! Also the ability to go back to a page I generated is super helpful, I always skip past one I actually kinda liked in my haste.
Also you don't often get the type of mood this one is giving off :P I like the moody rainy vibe of it!
One really good game jam theme generator I found ages ago (and I'm not sure if I just like it because it's quite pretty to look at) is this one: http://www.ludocraft.com/gigster/index.html (You have to enable flash to run it sadly).