1. Drill
Indispensable. I probably use my drill more than my router. It's used for drilling holes of all sizes and screwing things together. Corded or cordless doesn't matter, but corded will definitely be a lot cheaper. Cordless adds a lot of versatility as to where you can use it, but so does an extension cord.
2. Circular saw
This doesn't have to be a high end model (Porter Cable, Dewalt, Bosch, Milwaukee, etc). It can be a $30 Skilsaw. With a sawboard it'll handle all your straight cutting needs. Do invest in a good quality blade though. Good news there is that they only run about $10-$25.
3. Jigsaw
For curve or odd shape cutting needs. Not much else does this.
4. Electric sander
I'd get a 5" random orbit model over a 1/4 sheet pad sander. With the 5" ROS, grain direction isn't important. Also it's a bit more aggressive than a 1/4 sheet so it'll sand edges flush quicker. Also get sandpaper of various grits from 80 or 100 grit up to 220 grit. Anything finer than that should be hand sanded only. Also grab a rubber hand sanding block and some sheets of sandpaper. Can't get everything done with the machine.
5. Router of some sort
It doesn't have to be a full size router; it can be a laminate trimmer. I'd get a full size router though because the price difference is usually negligible. A full size router can do things a laminate trimmer can't either. I love my routers and not a project I build doesn't use one. Be sure not to neglect your router like Chad. It'll become lonely and depressed.
(just kidding Chad!
)
That's the basic list I'd have if I were starting fresh. Other hand tools not listed like clamps, utility knife, drill bits, router bits, etc, are what I would throw into a misc category. For occasional use there's nothing wrong with the black and decker or skil varieties.
An optional but highly recommended tool is a
pocket hole jig. It simplifies cabinet construction and makes a lot of joining tasks easier and a lot quicker. The one I linked to is a great starting jig.