There are about 6 or 7 hummers around my town, when I pass by one another i give a little double tap on the horn, they usually reply with a horn sound of their own. Much cooler than a wave and more people notice.
2003 Pewter H2 with Adventure Package, 20% tinted front windows, K&N aircharger filter kit, 3 screen DVD and Playstation 2 system. Soon to come: 37" MT/R's, Warn winch, XM and subwoofers.