This is really great.  SquaredUp, the company behind the amazing third party web portal for SCOM/OpsMgr, has launched a new open source community effort to build a catalog for SCOM for free, open source, commercial, paid management packs.  This is something Microsoft has in the pipeline for the 2018 release, though only for large vendors, but there's nothing really that great out there right now.   I just finished the webinar about the launch of this effort.  I'm installing the MP now!  It works on SCOM 2012-2016.  The respository itself is hosted on Github.