After playing with some numbers, I have come to find that there are 56 total possible stews. I have read elsewhere that there are 216 (6x6x6), but that does not take into account that if you number the herbs 1 thru 6 starting at the top left, stew with herbs 1/2/3 is the same as stew with herbs 3/2/1, or 2/1/3, etc.
So, here are all the combinations: 111, 112, 113, 114, 115, 116, 122, 123, 124, 125, 126, 133, 134, 135, 136, 144, 145, 146, 155, 156, 166, 222, 223, 224, 225, 226, 233, 234, 235, 236, 244, 245, 246, 255, 256, 266, 333, 334, 335, 336, 344, 345, 346, 355, 356, 366, 444, 445, 446, 455, 456, 466, 555, 556, 566, 666.
I have by no means tried them all... I have a few of my favorites, and will probably just stick to those, but have fun with these, and keep us updated with your results.

Before you did this, did you realize all of the stews have been well documented in the Stew Recipes thread? (you can click it below if you have not seen it.)

All the guides have all 56 recipes laid out for you.