So eliminating the obvious (the big knife, the small knife, a good stainless pan, an enameled dutch oven...)
These are a few of my favorite things:
These Bamboo, flat-ended spoons. Don't splinter, don't stain, can be used as spatulas (for small things) or stirring, scraping, deglazing, etc. I rarely start cooking without making sure one of these is within reach.
Citrus juicer (hinged squeeze type) -- lemons and limes are no match for its strength, and seeds don't end up in the juice
Microplane grater - medium fine works for cheese, zest, whole nutmeg, fingertips (oops)
Plastic collander - draining pasta, rinsing berries, draining eggplant
Those are the things that just plain get the job done. Lots of other things are big helpers, but merely a little faster or easier than the essentials. that would include:
Stand and stick blenders
Zyliss herb mincer (looks like a mini combine harvester)
Food processor
Rice maker
Microwave
What is patriotism, but the love of good things we ate in our childhood?
-- Lin Yutang