Parsing Discussion focusing on parsing data.
Console Development Specific development relating to the console, and driving the same.
Dialects/DSLs Discussion focused on the creation of dialects and DSLs using Rebol. Rebmu talk is appropriate here.
System Tools Discussion focusing on creating useful system utilities (e.g. replacement for grep, sed, awk, etc.)
General Tools Discuss various utilities written in Rebol here that aren't system tools eg. rebolbot, twitter
GUI development Developing GUI based applications in Rebol