Nutone makes a combo vent/ heater/ light deal... I've installed maybe 25 of them... for a small bathroom ( say 80 ish sqft) it takes only about 2 mins to get them hot. They do require thier own breaker, and wiring them is a little bit of work ( as you need 7 wires) not really hard, if you fallow then instructions... They can not be placed in the shower. They are also not very loud.
link (http://www.nutone.com/product-detail...roductID=10217)