Egg shells in the garden

I don't bother baking them, but crush them and put them in the compost heap with everything else. (Not I hasten to add anything cooked)

Egg shells are about 95% calcium carbonate (lime) and therefore can be used in exactly the same way (and with the same caution when it comes to lime-hating plants.)

(The other 5% is trace elements, including magnesium, and protein which helps holds the shell together - baking the shells destroys the protein and avoids any potential risk of attracting unwanted attention from animals, although I don't know how much of a problem that is in practice.)
 
Some members have tried using crushed egg shells as a slug/snail barrier, but I'll have to leave them to comment about its effectiveness because I've not tried it. 

I do the same to prevent against slugs and it seems quite effective..............just got to find something similar that works against whitefly!!!

I still use crushed egg shells around my young seedlings. Not sure how great it really works but I don't seem to have problems.

Since the half shells don't break down in the compost bin, it's easier to just rinse out the fresh shells, let them dry out (I chuck all mine in a carrier bag) and then crush the lot and sprinkle them around the garden. Eventually they get turned under and probably break down. They're in such small pieces by now it's hard to tell, but it's a better use of the shells than paying to bin them.

This calcium form would not break down quickly to be of help to the tomato. The soil should have some sort of powdered additive in place, or sometimes its more a matter of very regular watering that will prevent blossom end rot.