My iMac has gone through three different mice since I got it. It came with the default hockey puck rat, which I found abhorrent but usable. Then, my dad got me a Pro optical mouse, but I wanted one with more buttons, so I got a Starlogic 8D mouse with a trackball for a wheel.
The iMac still has the default keyboard, though. It's missing the End, (forward) Delete, and F13-F15 keys, though it still has that f*cking, annoying as hell help key. FYI, with special regards to Chem Geek, it has all the buttons he listed except Delete.
I finished the JUne issue of Macworld recently (yes, I do get behind on these magazines), and I found the opinion in the back by Matt Deatherage quite interesting. He said that Apple made a lot of the changes to the OS, like putting in certain features and taking out others, because the Next people wanted OS X to be just like Next. Apple may be taking the same stance with the mouse, this is how they do it and that's that, which is really stupid. Send your opinions to Apple, and maybe we can get them to change something.