I've tried many of the soy ice creams and there are some really great choices out there. Rice Dream has a crystal-y texture I don't care for, but if you can't have soy it's at least a choice. Tofutti puts some ingredients in their ice cream that aren't the healthiest, but that doesn't mean the ice cream doesn't taste good. I like Soy Delicious and I really like WholeSoy Glace, but since both are high in fat, my absolute favorite is WholeSoy Frozen Cultured Soy (think soy frozen yogurt)--it's utterly convincing AND low in fat! The only one I haven't tried is Soy Dream--I'm still waiting for it to go on sale.
Also, Edy's and Haagen-Dazs both make sorbets. Just be careful of Edy's coconut sorbet, it actually contains dairy (which "sorbet" is not supposed to do), and also be careful of eating too much fruit in the form of sorbet, which I've done before.