My strawberries never mold

They actually don't! I got a foodsaver vacuum canister to store my strawberries in, and the vacuum suffocates the mold.

I tested the vacuum, and found that inside the canister the pressure is 1/5 of an atmosphere. I wouldn't want a perfect vacuum, because deadly botulism bacteria grows only in the absence of oxygen.

I've never bothered to get any of the vacuum sealing bags. I also got the attachment for vacuum packing in mason jars. Unlike the canisters, the mason jars can be frozen (even with liquids if you get the freezer-safe jars). Unfortunately, the quality of the vacuum inside a mason jar is variable.

You can see how good the seal is by placing bubblewrap inside before sucking out the air.

I've also had good luck vacuum-packing

• ripe avocados: the inside never goes from green to brown. They keep for about three times as long, but they'll eventually go mushy.
• guacamole: it never turns brown.
• frozen vegetable soup
• frozen vacuum-packed omelets. They come out still smelling good.
• cabbage

I haven't tried blueberries yet.

Update 5-16-2006: My tomato juice keeps much better when vacuum-packed.

Update 8-1-2006: Romaine lettuce is still crisp and tastes fresh after a week. (Of course, our tongues evolved without vacuums around, so perhaps it degrades in ways you can't taste.)