Boxer is a DOS emulator designed specifically for the Mac. It provides a user-friendly front-end for emulator DOSBox, the source of its name. Boxer supports graphical smoothing, virtual drive importing, customized controls, full-screen mode, pausing, fast-forwarding, and CPU speed adjustment. It also provides support for MT-32 (music) ROMs, although it does not include them.
Importing a game into Boxer is as simple as dragging and dropping the DOS installation or executable folder onto the open application. Following the installation instructions should produce a .boxer file that can be used to immediately open your executable of choice in Boxer's internal DOSBox window. If you have or can find the game icon or box art, include it during the Boxer setup, and you'll build up a beautiful virtual collection of DOS programs in the application's Finder-based library.
If you just can't get enough of the old command line, it's also possible to go directly into DOSBox through Boxer, although the ease-of-use and completeness of the user interface makes your need to use this method all but irrelevant.