I rarely vote myself -- I feel that votes should be reserved for exceptional cases, and not simply "vote 'em if you got 'em". I think I'm in the minority, though.
in reply to Help me understand...
I use different criteria for the different sections... I'll vote an obfuscation up if it is really clever, like the Big One, or informative, like japhy's Obfuscation Review. I'll vote a Discussion up if, like this one, it brings up an interesting thought-provoking topic to discuss. I'll rarely vote a SoPW up, but replies that are well-written, generalizable, and informative will get ++. And so forth.
To get a -- vote from me usually requires extreme off-topicness, outright flaming, major lossage, or incredible stupidity on the part of the poster. I'll not give any examples, as I don't want to piss anybody off.