“Sacrilicious” was the waffle that was stuck to the ceiling, that Homer thought was God: “I know I shouldn’t eat thee, but …” followed by “Mmmmm… sacrilicious!”
My favorite is when Homer was naming several chief justices of the supreme court and gets stuck on Warren Burger - “Mmmm… Burger”
Sacrilegious.
Sacrelicious. According to the link already posted, in the episode “Homer Loves Flanders.”
A good one that hasnt been mentioned:
“Mmm…open face club sand wedge…”
I can honestly say, I had NEVER heard another human being exclaim “Doh!” before Homer did. Maybe “Arrgh!” or “Rats!” or some expletive, but never Doh.
before manny locks it:
mmmm…snouts
Here I am sitting in my class giggling like an idiot…
mmmm…horse doovers
My favorite one was when Homer was explaining why gambling was good to Lisa:
“You see Lisa, football is like ice cream. And gambling is like the chocolate sauce, and the nuts, and the whipped cream, and the crumbled up cookie things- Mmmmm…crumbled up cookie things!”
Originally, the writers just wrote the “d’oh” as “frustrated grunt” in the script, which Dan Castellaneta eventually developed into the “D’oh!” we all know and love by taking a Laurel and Hardy “D’owwww” saying and shortening it at Matt Groening’s suggestion.
http://www.snpp.com/other/interviews/castellaneta94.html
Then on the other hand, this page claims that “Doh!” appeared in a British story in 1952. Just like us Americans to take credit for something the Brits invented. 
my favorite? bart and milhouse go on the super-squishy-syrup bender. a large amound of bubble gum is popped.
“Mmmmmm… free goo.”
jb