I use RG59 on 50-ohm radio systems, but just as a matching transformer :-)
When I wired my house, I pulled 3 runs of cat5 to each plate except the wall phones - ethernet, phone, and spare - and I have already used the spare in 3 places for a second ether and for temperature monitoring. The price difference between cat3 and cat5 is low enough; running cat5 gives me more expansion options.
As for catv, I cringe whenever someone uses something without a foil shield. Too much noise leaking out makes it tough to hear the 145.25 repeater. I even saw one guy use speaker wire to extend his catv - and he had an Extra license :-(
