In the last two months I've cut my aspartame intake by at least 75%. Cut it completely out of yogurt, gum, mints, etc., and probably cut 75% of my diet soda intake, though I'm still working on cutting that down to 90 and then 100%. Anyway, here's an article about a new study that may instill fear in some, may leave others unconvinced, but either way aspartame just seems a wee bit evil to me. I know the studies and the article and comments and such are inconclusive. Guess it's always that way (especially when money and the money-serving FDA are involved), but either way, I'll be glad to be completely rid of it.
On another note, the absolutely best diet soda out there is Virgil's. It's microbrewed, sweetened only with stevia and xylitol (natural, nonchemical sweeteners), made with all-natural ingredients, comes in bottles (so no plastic or aluminum taste, plus very recyclable), and is absolutely delicious and worth every penny of the 1.39 you pay per 12 oz. bottle (about the same price you pay for a 20 oz. of much worse-tasting diet soda). They make root beer, cream soda, and black cherry cream soda. And it's owned by Reed's, the ginger company. Check your local health food store for some. It's awesome.