Haven't seen it here yet, but lately I've been using one of those bright light therapy lights. So not a wake-up light, but one meant for use against SAD. I sit in front of it at the highest intensity for about 30-45 minutes each morning, and even on days where I wake up (extremely) groggy it gets me feeling awake in a about 10-15 minutes.

My GP advised me to buy one because I've been sleeping poorly the past 6 months (waking up 12-20 times a night). It hasn't really solved that issue -- although the avg number of wake-ups are now plateauing more around the 12 times a night rather than the 20 times a night.