Emily Bites has a tip for making your own Taco Bowls with a muffin tin. The trick is to turn the muffin tin over and use the backside to cook the bowls in. The 6-inch tortillas form mini-bowls that way. From the site:
Sprinkle each tortilla lightly with water and stack them on a plate. Cover the top with another plate turned upside down and microwave the tortillas for 1 minute or until warm. Turn two 12 cup muffin pans upside down. Mist each side of a tortilla lightly with cooking spray and center it in the space between 4 muffin cups, creating a bowl. Repeat with the 5 remaining tortillas, forming 3 bowls on each tin (as pictured above). Bake in the oven for 8-10 minutes.
Once you have the taco bowls, you can fill them with vegetables, ground beef, shredded cheese, and other ingredients for your own taco salads.