Some cameras (AG-AC160/130) being examples have WB switches.
I have a three position switch A, B, and Preset.
You can do a wb and lock in the reading to A or B, giving you two calculated wb values you can use.
As for the Preset, it toggles between 3200, 5600 and VAR each time you push a button.
So, now you have four fixed options and with VAR you can dial in what you like if you happen to know the color temp.
WB options at the camera save you from adjusting WB in the NLE. I must say that Sony Vegas 12 does a pretty good job of fixing up bad color temp recordings but its clearly better to have it right from the start.
I love the 2x, 5x and 10x optical multipler on the AC160 on top of the 22x zoom - it lets me frame the white card up to about 55 feet away - saves me from having to go up close (most of what I do is at the back of theatres or churches).