Operation Flashpoint

Filefront
Includes screenshots, modifications, and maps to download.
http://operationflashpoint.filefront.com/

Finnish Defence Forces
Total conversion based on the Finnish armed forces. Includes downloads, backstory and weapon guides.
http://koti.mbnet.fi/fdfmod/

Gaz's Site
Offers maps and editing tools to download.
http://mysite.wanadoo-members.co.uk/MillsOFP

Jolt : Operation Flashpoint UK
UK resource for Operation Flashpoint downloads, news, resources, tutorials, forums and information.
http://www.ofp.jolt.co.uk/

OFP Editing Center
Site dedicated to editing and modifying Operation Flashpoint, providing help, tutorials, downloads, information and a forum devoted to editing.
http://www.ofpec.com/

Operation Flashpoint Network
Provides information, ingame screenshots, game introduction, modifying/scripting information a forum and regular news.
http://www.3dactionplanet.com/flashpoint/