Revenge of the nerds
For the Dad who's been on a computer run since Univac, there are many intangible gift items. BlackBerry, iPhone and Android all offer gift certificates for apps.
Maybe Dad is dying to play retro "Frogger" or the hot new "Angry Birds," both available as apps. Of course, that's when he's not playing chess at the dining room table with his pal, that Walter Matthau-lookalike.
Make sure Dad has good anti-virus and security software. Check with your own computer experts for the right system. Enhance the gift by overseeing the installation and cleaning up Dad's system. Make it a malware free Father's Day!
Buy Dad an external hard drive and if he doesn't know how, back up his system for him and set up the software to do regular back-ups.