I use a Spin Doctor truing stand mounted to the miter slot of my table saw, with a couple of dial gauges on magnetic bases for true and round. I get the wheel close with the cheesy plastic feelers on the truing stand, and then finish it up with the dial gauges. It's a nice, cheap accurate setup at $40 for the stand and $30 a piece for the dial gauges and bases (ignoring the cost of the saw of course).

I spend most of my wheelbuilding time though checking and rechecking spoke tensions to make sure they're nice and even. I find the gauge for round very useful since the mechanism on the truing stand has a tremendous amount of lash to it and is difficult to use precisely as a result.