Basilisk II is an Open Source 68k Macintosh emulator. That is, it enables you to run 68k MacOS software on you computer, even if you are using a different operating system. However, you still need a copy of MacOS and a Macintosh ROM image to use Basilisk II.

Thanks to http://www.dcemu.co.uk for the news and the hint for the next few following ones.

http://pleasantfiction.ipower.com/ps3linux/ps3bodega61/ppc/repodata/repoview/BasiliskII-0-1.0-0.20060501.3.ydl.bdg.html