I built a house a few years ago and searched Ask Slashdot for Ideas. Here is what I did:

* Two bundles of banana cable to every room back to a central location. Each bundle contained 2 x Cat5e + 2x RG6QS
* One bundle of banana cable over the jacuzzi tub for a small TV.
* Run an ethernet jack behind appliances. (fridge, stove, washer / dryer, and water heater)
* Electrical outlets in the eves of the house. Christmas lights are a breeze to put up and take down
* In the great room behind where I was mounting the TV I also ran in-wall rated HDMI 1.4a back to the central closet.
* I picked a room that in the future would be a media/theater room and ran power + HDMI to the ceiling and speaker wires in the walls.
* I never called $phone_company to install lines. The only lines to the street are power, water, and cable (for internet)

The last one has caused some problems as every service provider says your house is unserviceable since it is not listed in "the database".