I was very happy to find this cover this weekend:
Shonen Knife - Do the Bartman [originally from the Simpsons; co-written by Michael Jackson]
An all-girl Japanese band covers Bart Simpson. Yes!
Osaka Popstar & The American Legends of Punk - Sailor Moon [originally performed by Nicole and Brynne Price (--thanks Sarah!)]
An all-guy American band returns the favour, covering a Japanese cartoon theme. I stumbled upon this album yesterday at the library, but unfortunately the concept of aging punk stars covering anime themes is more exciting than the output. The American Legends of Punk refers to members of the Misfits, Black Flag, The Voidoids, and The Ramones.
Bart Simpson & Buster Poindexter - School Days [originally by Chuck Berry]
I remember the Simpsons Sing the Blues album was so cool when I was like 7. It's actually fairly listenable.
Hoja - Coney Island Baby [originally by Les Applegate]
You may recognize this as one of the songs Homer's barbershop quartet (The Be-Sharps) performs.
Captain Thorns - Baby on Board/Coney Island Baby
[originally by the Be-Sharps/Les Applegate]
Wow, while checking who originally did Coney Island Baby, I found this guy's site with a full-on cover of the Be-Sharps! Bonus, the man known as Captain Thorns even has a couple Moxy Früvous covers! Check out this cover of The Greatest Man in America.
Steinski's Simpsons Remix
I can't remember exactly where I got this from, but presumably from over at WFMU.