How to make a moving avatar?

Well the title says it all! I want to change my avatar and I was thinking of making a moving one...I saw a lot of them here from time to time.
So since I'm bored to look at the net, can someone tell me a simple way to make a moving avatar? Onegai...
~V
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P.S.I've been busy lately with some projects of mine but I'll be back soon...

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