Tomatoes can very well but I don't own canning supplies (maybe I'll get some for next year). That's not to say that you can't can without specialized equipment, but I'd be afraid of botulism if I didn't feel I had done my best to can them. Also freezing actually saves energy by packing already operating units.
Find a bunch of ripe (but not over-ripe) tomatoes. Roma are best for freezing because they have so much more meat than water, but any tomato will do.
Boil for 45ish seconds, and plunge immediately into waiting ice water. This makes the skins come off well.
Trim off anything tough or spoiled, peel skins and quickly remove seeds (it doesn't have to be perfect). Cut into manageable pieces (halves for roma, quarters for most regular tomatoes.
Pack in a bag, remove air (either by the old fashioned squeeze & suck method or with a vaccuum sealer) and freeze!
Corn also freezes well, but there's no real method... just cut off the cob (or put the whole cob in if you like) and freeze.