Yep Conan wrote or helped write on the simpsons. These are the episoddes he wrote as head writer.

Conan O'Brien:
[9F06] New Kid on the Block
[9F10] Marge vs. the Monorail
[1F02] Homer Goes to College
[1F04] Treehouse of Horror IV (wraparounds)


Not in the mood for cheese?
That excuse has more holes than a slice this fine Gorgombert!