Web Site: http://www.overcards.com/wiki/moin.cgi/iWitness
This software is actually an AutoHotKey script. It is substantially the same way as IdleMiner, without the screensaver function. However, it is completely free, but much less reliable and relatively contains a lot of bugs.
One of its advantage is that it has a network function. If you have multiple computers that are way competitor datamining, computers will be link via iWitness to avoid that the same table will be observed on 2 computers at the same time.
Note: If you use iWitness, you should also use FreePHG. (see below).