I read a bunch of great ideas a year or two ago. LIKE

1) Make one cupboard in the kitchen with a false rear panel with a built in
power bar so that you can plug in your phones, PDA's etc. and hide all of
the wires.
2) Extra outlets in the facia of the house for Christmas lights.
3) Glass Block Floor insert. (This will be going in for sure)
4) Exhaust vent and drain in the garage.
5) Access to Pantry cupboards from Garage side, so all old canned goods and
such are at the rear. (Easy for groceries)
6) More outside water taps.

etc. etc.