(submitted July 15, 2013 — Rick)
Tiki Wiki CMS Groupware (Tiki) is the Free and Open Source web application with the most built-in features. Other projects use a core+additions model; Tiki follows the all-in-one approach (but everything optional). This ensures that everything works together in every release (and avoids the "dependency hell" that plagues other applications).
Tiki is a community-driven project with a network of service providers (not Single-Vendor Commercial Open Source). Our "Wiki Way" of software development emphasizes collaboration on scale unlike most other applications.
With over 1 million downloads, an international team including 500+ developers with commit access, 10+ years of active development, and a new version every 6 months, the Tiki Community is amongst the FOSS projects with the most momentum.