I have to say that my KitchenAid mixer is the most used tool in my kitchen. I bought it when we were first married. B was in graduate school, and we lived in government subsidized housing. It was a very extravagant purchase at the time, but I have used it almost every day since, so it turned out to be a wise investment. I even use all of the attachments.
I make bread with the dough hook. The two bread recipes I make most are the French Bread and English Muffin Loaves in the recipe book that came with the mixer. I use the dough hook to knead the bread. Then, I oil the bowl and replace the dough and it rises in the same bowl. That makes for easy clean up.
I use the whisk attachment to whip butter, cream, and sometimes egg whites.
The flat beater is used the most. I use it for anything that needs to mixed. Mostly cookies... but also for pie crusts, scones, cakes, quick breads, and even meatloaf. I use it so much that I have worn through the white coating on two beaters. I am on the third beater in 20 years. I think creaming the butter and sugar that does that. I remember creaming the butter and sugar with a wooden spoon when I was growing up; that was a lot more work. Now I can measure other ingredients while the mixer does the work.
Remember, you can find more tools in the flickr pool.