The Chicago Diner is really way better than I expected. Best vegan milkshake I've ever had. It's pretty typical diner fare, done with fairly typical fake meats and stuff, but they do a really good job of making it not taste like reformulated soy. I love me some meat, but I have to admit that I liked this.
For higher end dining, consider Green Zebra. While I mostly don't like places with small plates of any type, Green Zebra is really good, and vegetarian (possibly vegan, I don't know). Great chef (same chef as Spring, and Custom House), good feel, and the food is creative, seasonal, and tasty.
Further south from Hyde Park, consider Soul Vegetarian (I believe on 75th). They do "soul" food, but vegan. Again, heavy on the fake meat products, as opposed to just well done vegetables, but this stuff is great. Fake meat burgers, and sloppy joes, etc. They also do "roasts." Fried okra, onion rings, etc. You won't come out of this meal feeling like you've just eaten health food.
Also, Soul Vegetarian I believe has a variety of options offered at coffee shops around campus (University of Chicago).
There is a pair of restaurants (Karyn's Cooked and Karyn's Raw, I believe) that do vegetarian stuff that people talk well about. I've only done the cooked version, and was "eh" on it. Some stuff that I didn't think would be done well was, but the milkshakes were really depressing after the Chicago Diners'.
Blind Faith in Evanston is quite good. Don't really have much else to say about it.
Ethiopian offers great variety for vegetarians (as do the plentiful Thai places in Chicago) that are not offered in many cities.
Also, the Devon area (not convenient to U of C at all) is plentiful with Indian and Pakistani places that are vegetarian friendly (some are vegetarian restaurants, some are not).
I'm not going to make any comments about the "animal/eco aware"ness of any of these places except what I've already said about the availability or 100%ness of their vegetarianness.