— General —
Official TF2 Blog
The name says it all: This blog is maintained by mighty Valve itself.
TF2 Wiki
The official Team Fortress 2 Wiki. Tons of interesting facts and info.
Steam Forums
The TF2-community on the steam website. Lower all your expectations. Enter at your own risk.
TF2 Backpack Examiner
Site for examining the backpacks of TF2 players (d’oh), but also providing good info on crafting blueprints
ubercharged.net
An excellent community-based editorial-site. Recommended reading.
Planet Half-Life
Boring site with standard content by moloch Gamespy/IGN. Probably not worth visiting. Listed only as a deterring example 
— Community —
Clan WDG
A UK-based TF2-clan. Not entirely sane, but great fun to play with.
— Custom Maps —
FPSBanana
Huge general customization site, including tons of custom maps. Mind that "huge" includes great stuff as well as a lot of crap. I don’t particularly like the site, but if I’m looking for something chances are I will find it there ...
TF2Maps
Mapping community site. Huge map database (sadly without rating and presented in a forum). Also does map contests.
TF2Wiki
A small collection of community maps.
CalculatedChaos
A site offering ratings for custom maps.
They also have a Custom Maps Server with playtests.
— History —
The Fort
The original stomping grounds of the Fort. Give it a glance and see what we talked about back in the old days.
Sadly only covers the period of TFC, its earlier content has been lost ...
Planetfortress
While also a Gamespy(now IGN)-owned site this was a premiere site for TeamFortress in the days of TF and TFC.
Besides hosting a lot of interesting community site it was also the home of the original Fort and the original TeamFortressSoftware-site (no longer accessible).
— Misc —
Keep Grinning
Private Blog of the equally funny as insane Ripsaw, who could probably elevate a phone book to the humour level of a Douglas Adams novel.
Chaospwns
This site is maintained by Chaos, computer wiz and former member of Clan WDG. The site is also increasingly covering professional TF2. He’s currently hosting his own TF2 server.
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