<p>I've run across this sort of thing on multiple websites and was wondering what it was called, does anyone know? <a href="http://twitpic.com/h77i/full" rel="nofollow noreferrer" title="twitpic.com">Here's a screenshot.</a></p>

I don't see anything obviously out of place.  If you're working with a very large database, you could try increasing your heap size by using the
```
-Xmx n
```
option in your JVM invocation.  This is usually not the best solution - only do with this when you know your working set size is actually bigger than the default heap size.
Are you using any complex data structures?  If you have circular references between objects, you might be preventing the garbage collector from cleaning up unreachable objects.  If you have any hand-written data structures, make sure that you explicitly null out references to objects that are removed instead of doing something like decrementing a size variable.