The tools you need will be partially dictated by the type of plane you are building. In general, these are a good place to start:
Good lighting.
More good lighting.
A little more lighting!
#11
6", 12" flexible steel rules.
T-pins in a couple of sizes.
A fine tooth razor saw.
80, 120, 240 and 360 grit sand paper with the 360 being wet or dry.
6" and 12" sanding blocks.
Balsa plane.
A collection of clamps.
Some wooden coffee stirs. (like at Starbucks)
2 oz plastic cups. (grab a few from the salsa bar at the local taco restaraunt)
30 min. Epoxy.
Thin and thick CA.
Carpenters glue.
Dremel rotary tool with an assortment of sanders, cutoff wheels and burrs.
Tweezers.
Scissors.
Allen wrench set (SAE or Metric as needed)
Small flathead and phillips screwdrivers.
Small sockets and wrenches. (SAE or Metric as needed)

That will get you through most of any build.
Another good resource is to check out Paul Johnson's website at www.airfieldmodels.com
You will find a wealth of information and ideas there.

A regular table saw is pretty useless in model building. If you wanted to add a saw, I find the bandsaw to be the most useful. Some people like a scroll saw, but I've very rarely used mine.
Another very used power tool is a belt/disk sander. These are not absolutely necessary for building, but are welcomed additions.

On down the road, you may also end up needing some other items such as:
Heat gun.
Covering iron.
Balancing machine.
Incident meter.
Throw meter.

One last word on tools. Be careful, collecting tools can become a hobby all to itself!

Scott