Here are some Half Life 2 links I visit involving game stuff you might find interesting

http://ocmapdb.wikidot.com/

http://www.blackmesasource.com/

http://www.obsidianconflict.net/?page=downloads

http://www.synergymod.net/

http://www.cry-of-fear.com/

http://www.moddb.com/mods/operation-black-mesa