I put celery in all sorts of stuff, I use it more like a herb than a vegetable if that makes any sense, and I easily get through a head of celery a week. It's absolutely fantastic with anything containing either tomatoes or mushrooms.
Apparently it's rich in phthalates (or something like that) that makes it a really good flavour enhancer, especially for 'umami' flavours.
Try it, the addition of a finely chopped stalk of celery, or celery leaf, to soups or pasta sauces is bloody yum.