Cpanel runs on three levels. WHM has the root panel, the reseller panel and then cpanel for the end user. It's pretty comprehensive.
I was just speaking to jag at the hideout an hour ago and saw a screen shot of hostgui http://www.hostgui.com
- it appears to be cpanel on PCP
- very impressive for those of us that like bells and whistles
Neither is free of course but both offer a large amount of services for the reseller and end user. (Host GUI is due *soon* apparently)
Felix has a free one he's building though dev seems to have stalled a bit in recent times.
interested me, but I never saw a running demo of it.
FreeVSD looks great but it's a different syle of hosting (virtual server hosting), and is apparently an 'intersting install experience'
Finally Cpanel has an 'upgrade' planned called Nocsoft though the release date for it seem to move faster than Carl Lewis