Price wise, it's hard to beat the
Rival Hot Pot, currently retailing for $12.99 at Target. Unlike most electric kettles, it does have an adjustable thermostat. The temperature ranges themselves are not marked, however. You may want to get a
digital thermometer and spend a bit of time learning what the maximum temperature for each setting is.
You might, however, want to get something 'cordless,' because cords are a HUGE pain. For some reason, variable temperature kettles are hard to find, but
Upton Tea has a nice model currently on sale for $36.80 (normally $49.95). There is, of course, Adagio's
utiliTEA. It's currently out of stock, but should be coming in very shortly. T-fal also has a similar contraption, the
Vitesse.
Also, T-Fal just put out a new gadget--the
Quick Cup--which looks iPod slick and will basically give you a cup of boiling water in 3 seconds. It's supposed to be more energy efficient too. I think right now it's only available in Great Britain, but with different adapters and such you could probably jury rig it for use in the US.