I also end up freezing ingredients more than full meals, but here are my thoughts:
I'll echo previous posts - beans freeze fantastically well. I reuse old cans (from canned tomatoes, usually), cut the top completely off and fill up with beans. Covered with their own juice, they freeze great even without lids for the cans.
Other things that freeze well - tomato products. I usually try to make double recipes of spaghetti sauce/pizza sauce/salsa whenever I'm having it for dinner and just stick the extra in the freezer for next time.
I do the same with brown rice. Since it takes so long to cook, I'll cook up a big batch, stick extra in the freezer and I have some "minute" rice whenever I need it.
As someone trying to be more vegetarian (I haven't quite given up all meat yet, but I'm getting there), I have lots of produce that can go to waste as well. Most veggies and fruits freeze great - I stick them in the freezer when they are about to go bad. Bell peppers (cut up), celery, tomatoes, fruit. All freeze fine. The texture isn't good for fresh eating, but fine for cooked items (soup, pizza, etc). The frozen fruit I use in smoothies.
You can use the microwave to defrost (obviously in plastic or glass, not metal). Microwave is about 10 minutes to full defrost for 4 cups of beans. But since I use the metal cans myself to freeze, I just fill the kitchen sink, or a big bowl with hot water and let the can sit in the water. It'll come free in a clump in about 10 minutes, and then a few more minutes, maybe 10 more, to totally defrost in a pan on the stove. I add a little water to the pan to make sure nothing burns. The beans are fully cooked, so I'm usually working on the rest of dinner while they defrost anyway.