Searching around online, I found there's a bunch of stuff on this. MLIA has a whole thread devoted to it. :P
here's a few good ones
(I figured this one out before I found it on MLIA)
Here Comes the Sun
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Here comes the sun, Dooden do do, Here comes the sun, and I say, it's alright.
(I couldn't figure out the instrumental)
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Little Darlin', it's been a long, cold, lonely winter.
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Little Darlin', it feels like years since it's been here.
In short: 656464566564454654 6456654245421 6456654245421
Tetris theme
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Do Re Mi
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Mary had a Little Lamb
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Figure out some more, fellow cell-geeksters.