vgmrips

I just love most of the soundtracks by Shin'en. I also noticed that some games use recycled music from previous games. For example, some scores by Manfred Linzner:

Asterix: Search For Dogmatix (GBC) - Alexandria, Memphis (Map) -> Kelly Club: Clubhouse Fun (GBC) - Egyptian (Unused)
Spider-Man (GBC) - Title Music -> Spider-Man: Mysterio's Menace - Title Music
NBA Jam 2001 (GBA) - Main Menu -> NBA Jam 2002 (GBA) - Main Menu
Music for Prince Naseem Boxing (GBC) -> Music for Mike Tyson Boxing (GBA)
Shin'en GBA Racer (Prototype) -> Tang Tang
Unknown Haribo Prototype - Main BGM -> Frogger Advance: The Great Quest - Credits
Maya the Bee: The Great Adventure - Level End -> Maya the Bee: Sweet Gold - Bonus
Tony Hawk's Pro Skater 4 - Flirting With Desaster (Track 2) -> Herbie: Fully Loaded - Downtown
Spider-Man vs Doc Ock (Java) - Main Theme -> Ultimate Spider-Man - Main Theme
Herbie: Fully Loaded - Track Select -> Tony Hawk's Downhill Jam - Steps of Marocco (Arranged by Martin Schioeler)
Herbie: Fully Loaded - City Harbor -> Tony Hawk's Downhill Jam - Hills of San Francisco (Arranged by Martin Schioeler; loosely based on)
Herbie: Fully Loaded - Main Menu & Amusement Park -> The Suite Life of Zack & Cody: Tipton Trouble - Skating -> The Suite Life of Zack & Cody: Tipton Caper - Title Screen -> Cars Mater-National Championship (DS) - Main Street (Last three was arranged by Martin Schioeler)

But most of the recycled melodies were made by Martin Schioeler:

M&M's Blast - Title -> Enchanted: Once Upon Andalasia - Giselle's House (partially)
Spy Kids Challenger - Unused Race BGM -> X2: Wolverine's Revenge - Weapon X (Stealth)
Music from SpongeBob SquarePants: Revenge of Flying Dutchman, SpongeBob SquarePants: Battle for Bikini Bottom, SpongeBob SquarePants Movie -> Music from SpongeBob SquarePants: Lights, Camera, Pants!
SpongeBob SquarePants: Revenge of Flying Dutchman - Gary, Go Home! -> SpongeBob SquarePants Movie - Cutscene (Loosely based on) -> SpongeBob SquarePants: Lights, Camera, Pants! - Driving Minigame (Reused from previous game) -> Chicken Little - Cluck House
SpongeBob SquarePants: Revenge of Flying Dutchman - Rock Bottom (Special Delivery) -> SpongeBob SquarePants Movie - Yoodle A Sea Doo -> Sigma Star Saga - Betrayal
SpongeBob SquarePants: Revenge of Flying Dutchman - Coral of the Story -> SpongeBob SquarePants: Battle for Bikini Bottom - Park -> SpongeBob SquarePants Movie - Coral Reef -> Ed, Edd n' Eddy: The Mis-Edventures - Pin the Tail on the Ed/Ed and Switch -> SpongeBob SquarePants: Lights, Camera, Pants! - TV Station
SpongeBob SquarePants: Revenge of Flying Dutchman - Over the Barrel -> SpongeBob SquarePants Movie - SpongeBob NoJob -> SpongeBob SquarePants: The Yellow Avenger - Rock Bottom (Loosely based on)
X2: Wolverine's Revenge - Canadian Wilderness -> Catwoman - Theater
X2: Wolverine's Revenge - Alert! -> Teen Titans - Self-Destruction (Music 7) (Loosely based on)
Extreme Skate Adventure - Scar Boss -> Kim Possible 3: Team Possible - Temple (Monkey Business Level 2)
Scooby-Doo! Mystery Mayhem - Boss -> SpongeBob SquarePants: Battle for Bikini Bottom - Boss (Loosely based on)
SpongeBob SquarePants: Battle for Bikini Bottom - Bonus -> Dr. Seuss' The Cat in the Hat - Up-Up-Up with the Fish (partially) -> SpongeBob SquarePants Movie - Credits (Reused from Battle for Bikini Bottom) -> SpongeBob SquarePants: Lights, Camera, Pants! - Dinner at Krusty Krab
SpongeBob SquarePants: Battle for Bikini Bottom - Chum Bucket -> SpongeBob SquarePants: The Yellow Avenger - Industrial Park
SpongeBob SquarePants: Battle for Bikini Bottom - Rock Bottom -> SpongeBob SquarePants Movie - Sea Cave -> The Sims 2: Pets - Pet Cemetery
Dr. Seuss' The Cat in the Hat - Cleaning Machine -> Crash Bandicoot Purple: Ripto's Rampage - Bonus (Loosely based on) -> Spyro Orange: The Cortex Conspiracy - Castle Cruisin' (First part only) -> Chicken Little - Town Hall (Second part only)
Barbie as The Princess and The Pauper - Got the Piece of Map -> Barbie and the Magic of Pegasus - Cloud Palace
Music from Kim Possible 2: Drakken's Demise -> Music from Kim Possible 3: Team Possible (Also, jingles from both games was reused in Kim Possible: Kimmunicator)
Kim Possible 2: Drakken's Demise - Shego Boss -> Barbie and the Magic of Pegasus - Caught Up with the Troublemakers
That's So Raven - Game Over 2 (Unused) -> That's So Raven 2: Supernatural Style - Lose
SpongeBob SquarePants Movie - Level Start -> Tak: The Great Juju Challenge - Level End
SpongeBob SquarePants Movie - Beat Final Boss -> SpongeBob SquarePants: Lights, Camera, Pants! - Beat Final Boss (Unused) -> American Dragon Jake Long: Rise of the Huntsclan! - Beat Final Boss
Teen Titans - Main Theme -> Teen Titans 2 - Main Theme
Teen Titans - Battle Theme 2 -> Teen Titans 2 - Map (Loosely based on)
Monster House - Boss Battle -> Spider-Man 3 - Main Theme
Music from The Suite Life of Zack & Cody: Tipton Trouble -> Music from The Suite Life of Zack & Cody: Tipton Caper

I don't think I missed anything.

Also, there was a music from Crash Bandicoot GBA games, that has recycled/reused music:

Crash Bandicoot: The Huge Adventure - Title -> Crash Bandicoot 2: N-Tranced - Title
Crash Bandicoot: The Huge Adventure - Jungle -> Crash Bandicoot 2: N-Tranced - Island Theme
Crash Bandicoot: The Huge Adventure - Bonus -> Crash Bandicoot 2: N-Tranced - Bonus

Also i found, that Sigma Star Saga had two unused songs. Second song is arrangement of Magneto's Lair from X2: Wolverine's Revenge.

Unused stealth music from That's so Raven was arrangement of stealth music from Bruce Lee: Return of the Legend.

Also, Die Wilden Fussball Kerle: Gefahr im Wilde Kerle Land reuses some songs and jingles from first game (Entscheidung im Teufelstopf).

Jingles from Tak: The Great Juju Challenge is similar to jingles from SpongeBob SquarePants Movie and death jingle from The Lion King 1 1/2.