Couldn't live without is a bit extreme. I do like my comfortable Op/Tech strap, my Giotto LCD cover, and my snap-cap lens caps a lot. I could live without them but I'd rather have them.
A black Domke gripper strap makes it easier and more secure to let the camera hang off of your shoulder and it looks much classier than the brightly colored STEAL ME straps that they ship with the camera. Besides, they ain't paying you to advertise for them.
For my end of the year spending I could have purchased a new 5D mkII or a couple of fancy lenses, but somehow rationality prevailed, and instead I got a much faster, more powerful computer, Lightroom 2, and upgraded to CS4. Less exciting, but much more productive. I've had them for about 2 months now, and it was definitely the right choice.
Fancy Circ-pols are easily $100, $150 made by companies like B+W. I don't use them in my subjects of choice, so I've never bothered to pick one up, aside from the cheapish Hoya that I bought a long time ago (mostly used it on film cameras). The big price difference may be that for modern autofocus cameras you have to use a circular polarizer rather than a linear, which are a lot cheaper.