There is a multi-band distortion in RiffWorks that allows you to distort any combination of low, middle and high frequencies. You can have a lot of fun with this one but it take a little time to master. Here's the instructions on how it works:
Multiband Distortion: This is where things get crazy. We can take our complete tone modifying effect with EQ and Compression and add different distortions to each band. You turn on the distortion by flipping the DISTORTION switch to the ON position for the band you want to distort. You then select the type of distortion you want to apply to that band using the SHAPE popup. Finally, you can decide how much distortion you want to add with the DRIVE knob.
There are several shapes in the menu. FUZZ is a basic distortion like you would find in a stomp box. The others are unique because they actually change the pitch of your signal. When using this on one band you create a harmonized signal of what you are actually playing and the pitch shifted version. DOWN shifts the signal an octave down. Listen. DD shifts the signal two octaves down and can sound completely outrageous with the right notes. UP shifts up an octave - this sounds good on just about everything when well balanced with the other bands. The others are trippy because they shift your notes by a 3RD, 4TH, or 5TH. Try soloing with one of these set on the MID band. Listen.
Check out some of the factory presets for TripWire to get a glimpse of what is possible. It is a complete "design your own pedal" kind of effect with full harmonizers, distortion, compression, and EQ. This one is a lot of fun...
http://www.sonomawireworks.com/tripwire.php