Yeah, desire to build a WHMCS replacement rising.
There remains the promise of
http://WHSuite.com but no word on progress at all. And then there's Blesta, which has promise w/the participation of 3rd party developers, yet w/o that is still pretty much just a billing platform for webhosting.
HostBill works nicely, when it works at all, and if you're really daring you can even take a chance on destroying your entire business each week by performing updates, which usually break something else that was previously working, but only a fool would consider that app now.
I'm actually considering going back to a simple script based system much like
http://prgmr.com/ - or at least re-deploying under a different brand for those services.