I use the whole tone scale all the time. The octatonic scale is pretty nifty for impressive-sounding runs. I've also been using the nine-tone (nonatonic?) augmented scale for some time, and have started getting into the use of the neapolitan major and minor scales, which are very cool. Unlike a lot of other symmetrical and "exotic" scales, the neapolitan scales have a rather tonal sound to them.