Ok - Dazren recommends that we do this as a Wiki thingy; so here we go:

48hrs - Speedster
Bad Boys - 964 Turbo
The Business - 928 + 924
Cannonball II - 935 (4?) replica
Cars (Pixar) - 996 C2 (Cartoon car!)
Getaway in Stockholm - 911 3.2
Gone in 60 Seconds (remake) - 996 C2
Gumball Rally - 911
Her Alibi - 356 cabriolet/speedster
Hollowman - 996
Le Mans - 911, 917
Local Hero - White 930
Risky Business - 928
Rogue Trader - 964 Speedster (red)
Spy Game - 912
The Freshman - 89 Speedster (red)
Top Gun - 356 speedster
Weird Science - 928
Who Dares Wins - 928S (burgundy)
Condorman - numerous black 930s and one flatnose

Street Hawk?