The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Repositories (1 member)
- Requirements (1 member)
- Requirements analysis (1 member)
- Resurgence Magazine (2 members)
- Reticulation (1 member)
- Reuse (2 members)
- Reviews (2 members)
- Revision control (2 members)
- Revolution (2 members)
- Richard Flanagan (1 member)
- Richard Stallman (1 member)
- Right Ordering (3 members)
- Ripping (1 member)
- Robert Macfarlane (1 member)
- Roel Loopers (1 member)
- Roots (1 member)
- Rosie O'Gradys (2 members)
- Rotation (1 member)
- Roundhouse (2 members)
- Routing (1 member)
- Rowan Atkinson (1 member)
- Rsync (2 members)
- Rsync.net (0 members)
- SFTP (2 members)
- SGI 1600SW (2 members)
- SQL (6 members)
- STV (2 members)
- San Francisco (1 member)
- Satish Kumar (2 members)
- Saving (2 members)
- Saw horses (1 member)
- Saw stools (1 member)
- Sawdust (1 member)
- Sawing (5 members)
- Scanning (1 member)
- Scenery (1 member)
- Scheduling (1 member)
- Schema (1 member)
- Scotland (3 members)
- Scott Hanselman (2 members)
- Scripts (3 members)
- Searching (1 member)
- Selecting (2 members)
- SemanticForms (2 members)
- SemanticMediaWiki (1 member)
- Semantic MediaWiki (7 members)
- Semantic web (1 member)
- Sessions (1 member)
- Sewing (2 members)
- Sharpening (1 member)