Things I found...

Guest strips drawn by Michael!!

Filibuster Cartoons - Guest Strip Ahoy
Robot Stories - "Retail Hell"
Sam & Fuzzy - Guest Strip #1 and Guest Strip #2
Book of Substitution - Guest Strip (To understand that strip best, it's apparently good to read this one first, then Mr. Lalonde's strip, then this one.)
Theater Hopper - Guest Strip
Comic Strip - "Sordid, Corded Affair"
Scary Go Round - Guest Strip #1 and Guest Strip #2
Diesel Sweeties - Guest Strip
Hate Song - Guest Strip
HER! [Girl vs Pig] - "her shiinng!"

Enjoy! Anybody know of any I missed?