I just want to share my experience with gel filters. ....My gel filters which came with my SB800 has been sitting in my bag for two years now, but I decided to use it last night and whoa, I should have known better. We were having a quiz contest in a tungsten lit room and my shots had casts of yellow from the bulbs and white from the flash. After inserting the tungsten filter and setting the white balance to tungsten, the lights were uniformly white...Not too natural, but the final output was better, to me at least. So guys, put those gel filters to use.

I use the gel filters in my flash quite often. Not just for correcting incandescent lights, try using it for portraits outdoors just before the sky goes completely dark and you'll get a nice warm image with very saturated blue skies (assuming 1:1 or 1:2 flash ratio).

Actually a friend of mine who's into wedding photography even got the whole set/bunch... He said it's of good use specially for CLS. :)

I prefer to use bottles of Gatorade :D