other things I have put in them are cooked buckwheat soba noodles, napa cabbage, brown rice, wild rice, mushrooms, sprouts, tofu, and even a little bit of greek yogurt. The sky is the limit.
Another way to make spring rolls is to use lightly steamed cabbage leaves as the wrap or collard leaves. I found that stripping a portion of the major vein int he center of the leaf helps it fold better. This is great for raw eating as well.
When I was in Brazil, using cabbage, chard, collard or kale leaves was a great way to reinvent a pot of cooked veggies and tofu from the night before, just wrap it up and you're good to go!