When I first started to access newsgroups on my Mac, I found that sometimes, after a binary download was complete, I'd be left with various .RAR files and at least a couple of .PAR or .PAR2 files too. A quick Google search for how to work with PAR files led me to the excellent MacPAR deLuxe, a free, simple and easy-to-use utility for Macs and PAR/PAR2 files.
MacPAR deLuxe works extremely well in its main function: analyzing and joining large archive files that have been downloaded from Internet newsgroups. Simply right-click a PAR file in Finder and open it with MacPAR deLuxe. The program will immediately start analyzing the PAR file and checking that you have all the necessary constituent parts to rebuild the original file, generally a RAR compressed archive.
After checking that you have all the correct files, MacPAR Deluxe starts the process of joining them together. This doesn't take much time at all (in fact, the process has become even quicker recently on Intel based Macs). As soon as the joining process is done, the program starts extracting the contents of the compressed file. What's more, MacPAR Deluxe can even repair and recover some problematic archive files.
Another feature of MacPAR deLuxe is is PAR creation. Simply select (or drag and drop) the files you're planning to upload to your favorite newsgroup and MacPAR deLuxe produces the PAR file for you.
If you're working with newsgroup binaries on a Mac, MacPAR deLuxe is a truly essential piece of software. It's simple, uncluttered, clear but most importantly: it works!