One of the best sites to check is http://indyethnicfood.com
. You can search by veg-friendly (these are rated by locals who eat at the restaurants, not "professional" reviewers; basically they might not have a lot of choices) and part of the city, cost, ethnicity, etc.
I love Indian food and think Shalimar and India Palace are the best, but Udupi is good too. Their food is a different style (different region of India) so it may not be as familiar if you normally eat other types of Indian food. But Udupi is the only all-veg place in Indy.
I found a Chinese place on the northside that has seitan! Only place in town I think. Check out Sesame Chinese Restaurant on that site.
Other favorites: Broad Ripple Brew Pub, Some Guys Pizza (and WB Pizza across the street has vegan choices), Yats (CHEAP!), Scholar's Inn, Santorini's, Mediterrano Cafe, Cairo Cafe, Three Sisters, R Bistro if you like fancy stuff. Good chains include Noodles & Co., Stir Crazy, Qdoba. I also really like the Peruvian place Machu Picchu but they only have two veg things (just really good ones).