Pitch-bend joysticks facilitate expressive trills, and pan knobs add spice. Just ask this MIDI-monitor monster.
Two weeks after helping a musician buy her first synthesizer, I checked back and was shocked to hear that she still hadn't touched the pitch-bend wheel. Are you getting all the expression you can from the joystick, knobs, and wheels on your gear? Even tiny movements can make a big difference, because our brains quickly tune out sounds that don't change. Try varying the panning of a percussive part slightly — either directly with a knob, or with a mod wheel mapped to an LFO. (Set the LFO to a triangle or random shape, and then use the wheel to move its level up and down.)
Sometimes the most ear-catching results come from pitch-bending sounds you wouldn't normally think of as pitched. I like to loop MIDI drum patterns and then overdub both subtle and drastic pitch-bends to create alien grooves (see Web Clip 2). (For more about David Battino's work, visit batmosphere.com.)