Wineskin is a tool used to make ports of Windows software to Mac OS X.  The ports are in the form of normal Mac application bundle wrappers.  It works like a wrapper around the Windows software, and you can share just the wrappers if you choose.

Basilisk II is an Open Source 68k Macintosh emulator. That is, it allows you to run 68k MacOS software on your 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. Basilisk II is distributed under the terms of the GNU General Public License (GPL).

Win 3.1 in the browser