Even though I dislike the Shipoopi GAG (which takes up two minutes of time just to celebrate a touchdown!), I find the song incredibly catchy and listen to it outside of the show itself. Loses a couple points for not being an original creation, but the arrangement of it was great.
In terms of commercial parodies, "Double Fresh Gum" always remains enjoyable. It seriously sounds like something you'd hear on a TV ad.
All the songs from the various Brian/Stewie road show episodes are fun. Though I think I'm the only one who prefers "You And I Are So Awfully Different" to "Road to Rhode Island".
"FCC" is classic too, with some funny lyrics ("Cause ya can't say 'penis'"), though again, it borrows the main melody from "Volunteer Fireman Picnic".
"I Have James Woods" is another fave. The various visuals to go along with it work, too.
It's not a huge favorite of mine, but I do like how "I'm Gonna Make You Famous" cuts into the end of Peter's song and comes back to it after the commercial break, making it look like he held that last note for two minutes.
I could listen to Quagmire's "Make 'Em Laugh" over and over. Needed to be longer (something I don't often say for this show!).
"My Drunken Irish Dad" is a fun Irish drinking melody. Does that happen to be parodying any song, or is it an original creation?
"Oz" parody: "Scrub scrub here, scrub scrub there, whether you're white or bronze, a man can wash another man, in the merry old land of Oz!"
Finally, "You Have AIDS" and "Vasectomy" are amusing songs out of unlikely song subjects. I especially like the part in the Vasectomy song where the barbershop quartet goes off on a tangent about sexism and the woman's breasts running the sensitivity training seminar.
