Boing Boing has posted the awesome MP3 Whistler's Delight, a mashup by DJ Riko that mixes 22 whistling songs. Here's the list of songs according to DJ Riko's site:

Peter Gabriel – Games Without Frontiers
Bangles – Walk Like An Egyptian
Credit to the Nation – Teenage Sensation
Brother Bones – Sweet Georgia Brown
J. Geils Band – Centerfold
Earl Hagen – The Fishin’ Hole (Theme to the Andy Griffith Show)
Bernard Herrmann – Twisted Nerve
Scorpions – Wind of Change
Bobby McFerrin – Don’t Worry Be Happy
Muzzy Marcellino – 4:20 a.m.
Otis Redding – (Sittin’ on) The Dock of the Bay
Roger Miller – Robin Hood
Air – Alpha Beta Gaga
Honky – The Whistler
The Lovin’ Spoonful – Daydream
Rick James – Loosey’s Rap (Loosey’s House of Trix Mix)
Adam Ant – Something Girl
RZA – The Whistler
Guns N’ Roses – Patience
Dwarf Chorus - Heigh Ho
X2 – Trigga da Whistla
Handsome Boy Modeling School – Rock n Roll (Could Never Hip Hop Like This) Part 2

Definitely worth the download; other mixes/mashups on his site are pretty cool too...