Here's an idea fro a topic: What purchases have met or exceeded your expectations and why.
I'll start with my D800. For those of you who suffer fools like me gladly, you may recall that I bought the D800 primarily to make illustrations I use in operator's manuals and other documentation I do for my clients. I was keen to get high resolution because I don't always know what I want to use in an illustration, and the ability to crop and zoom to a feature I want to emphasize seemed useful to me, as that is what we did in the film days, and I wasn't getting good results when I cropped to much with lower resolution cameras.
I am very satisfied with this capability, especially coupled with Photoshop CS6 where I can move things around to improve the overall image. We can't always control the angles when we photograph some of the equipment, nor can we control the distance to the subject: these are not product shots for advertising, but documentary photographs of equipment in operation. I can take one photo, crop in, rotate, highlight, annotate, and change exposure very quickly, allowing me to use on photo for several different purposes. I get my work done much quicker now, with results better than the Kodachrome days and with no repeat trips to the photo lab.
The D800 exceeds my expectations, and although it doesn't make me a better photographer, used with the new CS6 it makes me look like I'm a better photographer.