My brother-in-law(-to-be) read about someone who had written recipe filters for vegetarian and for vegan diets. He contacted the guy to ask if he'd do the same thing for gluten free, and now he has! The developer admits that he probably missed a few things that should be excluded (since GF gets so complicated), but there's a button to report a recipe that isn't actually gluten free, so we can help him refine his filter. That said, in my (very) little bit of poking around with it, I haven't seen any problem ingredients yet!
Find it at
http://cookglutenfree.net Happy cooking!