Dude! I live on sandwiches!
I highly recommend any of the Yves soy deli slices, or something similar if they're not available in your area. They make fake boloney, ham, turkey, salami, roast beef and cajun chicken slices that are VERY tasty! I make a sandwich with two slices of deli "meat", some mayo and/or mustard and lettuce and I'm ready to go. Sometimes for variety I'll add cucumber, tomato (although that tends to get mushy if you're taking it to work or school), sprouts, red or green pepper, mushrooms, etc.
Also very good is a roasted veggie sandwich, with roasted eggplant, red pepper, onion and portabella mushroom. Mmm. You can use pita pockets and put hummus, tabouli (a mixture of couscous and minced veggies) and sliced vegetables like cucumber and tomato in it, that is extremely tasty and very healthy.
Basically any combo of veggies and condiments is good. Cucumber and sprouts go really well together with a mayo or salad dressing. I also love dill pickle and mayo sandwiches, although I'm sure that's an acquired taste.
I enjoy peanut butter and banana on occasion, futureguineamom. I will have to try the peanut butter and brown sugar, sounds very good.