ARJ

The ARJ format was fairly popular in the first half of the 90s. A few, but not very many archives on Download Central use it.

Best put the executable somewhere in your path. On a genuine DOS installation, the DOS directory is a good place, in DOSBox, the folder that is mounted as C. Both WinZip and WinRAR 2.06 can serve as a Windows 3.1 front end.