Mac users interested in Merger by andreas schwarz for osx generally download:
Merger is a Mac OS X application that allows you to recombine split binaries. This is useful for files you might find on usenet (like the ones you might find named “file.divx.001″, “file.divx.002″, etc).
What Merger isn’t for is to combine separate files that weren’t split to begin with – such as combining two separate MP3 files into a longer song or two video clips into one clip.