I never ever (hardly ever) do graphics, much less GUI apps. So when I do, it is always a chore. But for fun I just whipped up a simple memory visualizer for ruby in less than 100 lines:
(key: String = gray, Array = green, Numeric = black (no fixnums), Class = purple, Hash = blue, everything else = red)
This has zero actual value to finding things out, so I will probably not release it.