Other than eggshells, did you know you can also use fish heads and aspirin as fertilizer for your tomato plants? Check out this post from Grow Better Veggies. Now I don't know where you're going to get the fish heads, but she got them from a restaurant where she grow for. David from Segua Ania also has a post about using aspirin as fertilizer, check it out.
I mean... really... fish heads?!?!
To add on to that, you can also put shrimp, crab, or lobster shells. Doesn't it sounds like the kitchen garbage bin?