There are four different envelopes you can apply on a per-item basis: volume, pan, mute, and pitch. Of the four, pitch envelopes are by far the most interesting and useful. By default the range is +- 3 semitones. That's ok, but you can change that, allowing you to do wild pitch swoops. Additionally you can quantize the pitch.
The limitations of pitch envelopes is they are item-only, and don't work on MIDI. But for MIDI pitch bending you can refer back to the ReaControlMIDI post.
So yep, pitch envelopes, give them a try.