This movie had an unreasonable influence on me as a kid...as cheesy as it is, it still holds up as one of my top ten favorite movies.
It's my favorite movie of all time, even though it's one of those movies that I don't expect anyone else to like. It's just a shot of joyful nostalgia right into my veins every time I watch it.
Explorers, the Ethan Hawke and River Phoenix movie from the mid-80s, is my #2 for the same reasons.
The movie is obviously technical garbage but one thing it did well was capture that early hacker counterculture spirit. I think a lot of us can appreciate that for the warm blanket it is and forgive its technical accuracy and story flaws.