The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Lenovo (3 members)
- Libraries (9 members)
- LibraryThing (2 members)
- Libre (1 member)
- Lighting (1 member)
- Lightweight markup languages (3 members)
- Links (5 members)
- Linux (8 members)
- Linux-voice (0 members)
- Category:Linux (0 members)
- Literature (2 members)
- Little Creatures (3 members)
- Living (3 members)
- Local history (1 member)
- Localisation (2 members)
- Log404 (1 member)
- Log entries (0 members)
- Logging (1 member)
- Logic (2 members)
- Logs (1 member)
- Luddism (1 member)
- MGA (1 member)
- MIME types (1 member)
- MacKennal Street (1 member)
- Mac OS (1 member)
- Mail (1 member)
- Making (10 members)
- Manifesto (3 members)
- Manton Reece (1 member)
- Mapping (3 members)
- Maps (3 members)
- Marco Arment (2 members)
- Markdown (3 members)
- Market Street (1 member)
- Markup (1 member)
- Marrion Zimmer Bradley (1 member)
- Marvin (2 members)
- Materials (2 members)
- Maximums (1 member)
- Mbox (1 member)
- MediaWiki (23 members)
- Meetings (5 members)
- Meetups (6 members)
- Melbourne and Mars (2 members)
- Menorca (1 member)
- Metadata (1 member)
- Methodologies (1 member)
- Microformats (1 member)
- Migrating (2 members)
- Minimalism (1 member)