It gets made fun of a lot, but personally I believe Hackers had the most realistic depiction of what hacking is like to hackers of any movie. Definitely one of my favorites.
I seem to remember in the film the two guys Razor and Blade who had that pirate broadcast 'Hack the planet' actually existed as well.
A friend of mine was arrested then for owning the cellular hackers bible which was considered forbidden knowledge. Crazy how far we've come now, you now longer have to go through an elaborate scam to social engineer a telecom employee just to get some basic information on how a POTS works.