Rebol is a modern interpreted language where code is data. It isn't object oriented, but has objects. It isn't a functional language but has first class functions. There are virtually no syntax rules or immutable keywords, making it ideal for developing domain-specific "dialects". - Stackoverflow tag
A low activity chat group on stackoverflow
Port Rebol2 code to Ren-c Trello
Carl Sassenrath's original Github repository has been inactive since 2013. Of historical interest only but you can build r3alpha from this.
Brian Dicken's fork known as ren-c is the main active branch and this site addresses the changes arising from that.