Got me a few of these:

» Wormie the water sensor

They look simple enough and they're inexpensive. I originally wanted one of the metal staff/dial hygrometers...couldn't find them, and seeing that I've gone through 4 or 5 already (they'd invariably fail on me) but those look simple and pretty much fool-proof (dark means there's enough water, pale means time to water).

:hippy: