Weird Al Yankovic is a pretty prolific writer of Comedy music. He's been doing it since 1979 and has sold more than 12 million albums. Nice work Al. Here are a few of my favorites (feel free to post your favs in the comments).
So after doing some quick searches it looks like Weird Al songs are embeddable in sites, but i can link to the video directly - it's just a click away. I've included the original song that the parody is based off as well.
White & Nerdy (34 million views - not bad! - based off Chamilionaire - ridin' dirty)
Amish Paradise (Coolio - Gangsters Paradise)
Fat (Michael Jackson - Bad)
Eat it (Michael Jackson - Beat it)
Gump (Presidents of the United States of America - Lump)
Smells like nirvana (Nirvana - Smells like teen spirit)