I know I have contributed to the java questions on stackoverflow. I have worked in java on and off for 14 years, but the java frameworks, e.g. Axis (of Evil), are often quite over-complicated. The questions are there because of employment and difficulty, not interest and ease.

That said, when I am prototyping, or doing a quick tool, it's usually in Perl. Quicker to write, and runs quicker as well (when single threaded). At least if "quicker" involves I/O, caching in hashes (maps) or sorting/searching. Java is quicker than Perl if you are twiddling ints, or throwing all your data away just after the network gives it to you, though :-)

Ruby is nice too, but I have done quite a bit less of that.