The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Paranoid android (1 member)
- Parlapa (1 member)
- Passwords (1 member)
- Paths (1 member)
- Peak oil (1 member)
- Pecl (1 member)
- Penguin Classics (2 members)
- People (7 members)
- Permanence (1 member)
- Personal email archiver (1 member)
- Perth (3 members)
- Perth Heritage Days (1 member)
- Perth Linux Users Group (1 member)
- Peter Lawrence (1 member)
- Philosophical Transactions of the Royal Society (1 member)
- Philosophy (1 member)
- Phoebe Ayers (1 member)
- Photo maintenance (1 member)
- Photographs (3 members)
- Photography (9 members)
- Photos (3 members)
- Photos with no known author (0 members)
- Php (0 members)
- PhpFlickr (1 member)
- Phpcs (1 member)
- Phpunit (1 member)
- Physicality (1 member)
- Piccadilly Jim (1 member)
- Pink Dandelion (1 member)
- Piwigo (3 members)
- Place (12 members)
- Placeblogging (6 members)
- Planes (1 member)
- Planet Freo (11 members)
- Planing (2 members)
- Planning (2 members)
- Plugin (1 member)
- Plugins (9 members)
- Podcasts (2 members)
- Point Counter Point (1 member)
- Politics (4 members)
- Popups (1 member)
- Porting (1 member)
- Portraits (1 member)
- Posts written when drunk (3 members)
- Preservation (2 members)
- Printable WeRelate (4 members)
- Printing (1 member)
- Priorities (1 member)
- Production (1 member)