I've got several sites (for a nonprofit org) and am wondering if anyone knows of an Open Source and Free webhosting control panel.

Working with a non profit and also just using it for my friend's sites, I just don't have the cash to plunk down for a commercial package.

Take a look at WebCP.
You can find it at
http://webcp.can-host.com/

If you do a search here there are a couple of threads with a fairly comprehensive list of free or nearly free options.

We wrote a free one that we use, http://www.freehostingsolutions.com - soon to be simplecp.com - but we are updating it and adding more features, should be back online mid-june