Cable TV, Cat5 or 6, a lot of separate circuits for lights, a lot of outlets, tall ceilings, a drain or two in the floor, overhead storage, outside lighting, security system, outlets in the ceiling, outlets in the corners in the ceiling, one switch to turn on minimal lighting so you can see your way around at night without turning on every light.
Take pictures of the framing from inside. Take pictures of where your electric wiring runs. Take pictures of any plumbing that may be hidden later. If you have to run any circuits later and you have finished walls, pictures will come in VERY helpful.
Before you have any piece of equipment starting, have a notebook loaded down with what you want. Once the equipment moves in as far as any backhoes, dozers, Bobcat, check off what you expect and get done. If the garage or pole building is detached and you are tying into your house panel box, make sure you run some underground conduit with a large diameter. This will allow for any future wiring to be ran. Add in some twine, or even run some CAT6 wiring, and maybe even some 12/2 w/g through the conduit for future use.
Add in some telephone jacks around the perimeter of the building on the inside. Add some outlets on the outside. Add some outlets under the soffit in a couple key areas. Add some outside floodlights to point down the drive and to also point out back, point towards the house.
If you have to run electric from the house out, add a switch IN the house that you can flip to light up outside lights of the garage. That way, if you are in the house and hear some strange noises, you can flip a switch in the house and light up the perimeter of the building. Anyone that would think of breaking in would be scared shitless once the lights came on.
There is probably a lot of others that I can't think of at the moment, but wish I would have done when I built my garage.
