There are some tools, everyone should have installed on his or her computer, when it comes to usenet.
Most tools are optional, because today's newsreaders already have repair and unpack engines included.
But having these programs on your system will come in handy, if the newsreader is not capable of repairing or extracting the downloaded files, because of a wrong par set, or so.
As most files on the usenet are packed into RAR files, so it's probably not a bad idea, to have a program installed capable of handling rar archives.
On a Windows machine Winrar 
would be a good choice here, on a Mac you can use UnRarX .
Also 7zip is pretty comon.
A tool like Quickpar is also a good choice in case some files are broken.
If you want to post stuff to the usenet, then you should check out JBinUp , Camelsystem Powerpost yEncBin Poster.
And, of course, stunnel for all the programs which have no build in SSL engine.
