If you want to play around with classic Mac OS without downloading and installing anything, I made a browser port of PCE (a similar emulator): http://jamesfriend.com.au/pce-js/
I have rather fond memories of using this while I was in high school (in the mid-to-late 90's). Considering that I didn't have a Mac at the time, it was one of the only ways I could play around with a real Mac (albeit a black and white one with an old version of the Mac OS).
The other options at the time were:
1) Shapeshifter, which ran on top of UAE (an Amiga emulator). It was basically unusable on a 486.
2) Executor, which was a clean room implementation of a 68K Mac. I probably spent the most time with this because it supported some reasonably recent programs and wasn't terribly slow.
> Mini vMac requires a ROM image file to run, and so can be legally used only by those who own a 680x0 based Macintosh.
Dangit.
So is there any way to legally buy an old-timey ROM image, the way you can buy a legal Amiga Kickstarter ROM from Amiga Forever (http://www.amigaforever.com/)?
Knowing Apple I'm guessing the answer is "hahahahahahahahahahahahahaaaaaa o my sides", but hey, you never know...