Richard Callaby's favorite geek movies are:

1. Sneakers
2. War Games
3. Hackers
4. Anti-Trust
5. Startup.com
6. Triumph of the Nerds

Mine are:

1. Minority Report (I loved that pre-crime interface! Oh, and you must check this probably-not-intended-for-public-consumption page at Microsoft Research: http://research.microsoft.com/~dcr/minority/functionality_01.htm)
2. Blade Runner
3. War Games
4. Matrix
5. Lord of the Rings Trilogy

Hmmm... Several of mine aren't about geeks per se, but blissed out my inner geek (I wish I didn't look for matchup errors, rendering artifacts, and kinematic mistakes during movies, but I read Starlog far too much as a youth...)