JigSaw's primary use is for joining files split with applications such as Master Splitter for Windows.
JigSaw offers PAR and RAR support. It also attempts to veryfiy that all of the parts are present.
JigSaw creates a Join/Split/PAR queue as you add files to the window. JigSaw sorts files of varried types in to the correct lists allowing you to drag, part, rar and par files to the window all at once and drop them on either the split, par or join lists.
JigSaw offers a built in media player as well as offering expanded viewing capabilities via jplugs like the zMediaPlayer.