Omi Vaidya:
The Office: The ITTech guy
Arrested Development episode: The Immaculate Election

Brian Baumgartner:
The Office: Kevin Malone
Arrested Development episode: Burning Love


Phyllis Smith:
The Office: Phillis Lapin
AD episode: The Immaculate Election


Ed Helms:
The Office: Andy Bernard
AD episode: The One Where Michael Leaves

Craig Robinson:
The Office: Darryl Philbin
AD episode: Switch Hitter

You forgot Lonny (Sea Monster) as one of the greatest flamers of all-time: T-bone. Still, great pick.

Oh man! I can't belive that. I fixed it, and here's the info for him.
Patrice O'Neal:
The Office: Lonny, a warehouse worker
AD episode: Top Banana

Ed Helms actually played a good part. Everyone else was in a scene for like 5 seconds.

H-I-L-A-R-I-O-U-S.

Oh I knew that was the IT guy! Haha, I just rewatched that episode today and I was like "Hmm, is that the IT guy?" Haha. Yay.

Just noticed one more:
Season 3, Episode 11 (Family Ties) - link plays Congressman John Van Huesen. He was also played the Captain of the boat on "Booze Cruise."

Nice catch!!!

Patrice O'Neal is absolutely hilarious.
"Did you burn down the storage unit?"
"Oh, most definitely."