I spent a few minutes looking for this list, without any good results. So here it is in full, with extra info.
Family Guy Episode 115 Ocean's Three and a Half - Video Clip
In this episode, Stewie falls in love with Joe and Bonnie's beautiful baby girl named Susie. Stewie decides to write a song about her and calls it "Susie." Brian says the song is horrible and calls him out for writing a song about a girl, because "there aren't a million of those already." Stewie says, "Oh Yeah? Name 20!"
Here is that list.
1) Rosanna - Toto
2) Roxanne - The Police
3) Michelle - Beatles
4) Allison - Pixies, Elvis Costello
5) Sarah - Thin Lizzy (Sara - Starship / Fleetwood Mac)
6) Angie - The Rolling Stones
7) Brandy (Mandy) - Barry Manilow, (or "Brandy (You're a Fine Girl)" by Looking Glass)
8) Mandy *
9) Gloria - Shadows of Knight (Van Morrison)
10) Cecilia - Simon and Garfunkel
11) Maggie May - Rod Stewart, The Beatles
12) Jessica - The Allman Brothers Band
13) Nancy - Frank Sinatra14) Barbara Ann(e) - The Regents, The Beach Boys
15) Billie Jean - Michael Jackson
16) Layla - Derek and the Dominos (Clapton/Allman)
17) Lola - The Kinks
18) Polly - Nirvana19) Helena - My Chemical Romance
20) Jenny from the Block - Jennifer Lopez
Name 6 more:
1) Sherry (Baby) - The Four Seasons
2) Laura - Frank Sinatra
3) Wendy - The Beach Boys
4) Maria - Ricky Martin, and others
5) Peggy Sue - Buddy Holly
6) Minnie the Moocher - Cab Calloway
Name 5 more: **
1) Tracie - Level 42?
2) Jean - Oliver?
3) Jane - Barenaked Ladies4) Mary Anne - The who
5) Elenor Rigby - The Beatles
*Brandy was the original name of Barrry Manilow's song, but was later changed to Mandy due to confusion with the same song by Scott English. This may be a homage to both songs, listing them in order.
**With the obvious exception of Eleanor Rigby, the last 5 songs are pretty obscure, but are possibly the version performed by the bands I listed. I think they easily could have found some more mainstream songs to throw in at the end, like Molly (Sponge), Maybellene (Chuck Berry), Veronica (Elvis Costello), or they just threw in these randoms to confuse people like me making these stupid lists.