I like the Speedpass concept, letting you pay for a variety of things (starting with Mobil gas) just by waving a little transponder near a sensor. A similar concept is behind the EZ-Pass system for toll booths, and I definitely love driving through toll plazas without having to fish for change. or even (99% of the time) wait in line. The fact that Speedpass is expanding, working at most Mobil and Exxon stations, and now at a bunch of McDonald's and at some Boston-area supermarkets, is a good sign. I think it could go far.
At one point I had a Speedpass connected to my business Mobil card, but that account got cancelled. Y'know, the little Speedpass fob is still on the keychain I carry around every day. I should get a new one... and keep wearing my nice Swatch.