I do only a small amount of cooking in our house, but I do a lot of cleaning up and putting away. About six months ago Sara brought home these glass storage containers with tight snapping lids, and I was amazed at how much BETTER they were than the old plastic stuff we'd used for years. Besides helping avoid leechy chemicals that come from plastic, these things have a satisfying heft, stack and clean easily, are clear so you can actually see your food, can be heated up and lock so tight they make the engineering guy inside of me squeal with delight. I recommend them heartily.
Here's a great testimonial from Boing
Boing about the awesome tightness: "I have biked with one filled with soup and arrived at my destination without a drop missing (something I definitely couldn't do with my old plastic ones), and I didn't have to waste another bowl in order to microwave it."