Pasta is always easy, and not only marinara. I'm making mushroom stroganoff tonight, and pasta e fagioli, herbs in olive oil, puttanesca (sans anchovies), etc. are easy, healthy options as well. Ethnic cuisines such as Indian and Thai are also often meatless, especially Indian.
I made this last week. It's a one pot rice dish with cabbage and chickpeas and certainly didn't taste
vegetarian =)
Soup is another good choice. Here are some links:
Wicked Good Vegetarian Chili - Don't expect standard chili flavor, but I really like this. TVP is a meatless ground alternative. I use the same amount of bulgar instead as I don't much like TVP.
Ultimate Vegetarian Chili - More of a standard bean chili, another good one.
Thai Cashew Stew - A curry experiement that went south on me one day. It turned out to be a really good soup, though.
Lentil Soup - Good, easy and hearty.