One great exercise I found is a four-string, four-finger pattern. Run it up and down the neck (I do it from the first through twelfth frets) and across the fretboard (E-A-D-G, A-D-G-B, D-G-B-E).
I found it effective for getting my left and right hands in sync as well as practicing my muting for every finger.
I actually use it as a warmup exercise. Nice way to get the fingers warmed up and to get the hands working together.