I've recently become obsessed with Joshua Redman's "noises" in his album Momentum, largely because of the effects produced that complement his sax sound so well (in my opinion).
One of my favorite effects includes the harmonizing of some melodic lines. At first I thought Redman just layered several tracks with himself playing the different lines, but then I saw him live, and he was able to create that "moving sax chord" sound in person as well. Shameful plug, I think I saw KT Tunstall use it too on Jools Holland. Does anyone know what kind of machinery/pedals are used to harmonize with you as you play?