Who could forget Tron? That's the quintessential "computer" movie. Way ahead of its time in digital effects, and the concept of being inside a monstrous computer that was bent on world domination was quite fun to take in. It even had "bits" as sidekicks. :)
How about the "Max Headroom" TV movie? That one, you had to be a true geek to appreciate. Also, Buckaroo Banzai was geeky in it's own special way (the main character was a geek-chic polymath)!