There's nothing like burning a few steaks, grilling some veggies, rubbing your belly... then spending 20 minutes scrubbing inch-thick gunk off your grill. Luckily, there's hope from Lifehacker. Just throw your grill in the oven:
"I scrape the big clumps off (otherwise when you cook it you get a lot of smoke) and then I put all the parts in my oven and set it to the magical "self-clean" setting. The oven bakes everything at a really high temperature (900 degrees on mine) until there is nothing but carbon lightly clinging to your grill parts. Let everything cool down and Voila! Clean grill (and oven)."