A link list:Gaia Links:Writers Forum Link List – Writer’s forum link list. This is pretty self-explanatory. A lot of links for a lot of things.
Think Tank – Think tank idea box
Prompt me! Words, phrases, and images to help you write. - A thread full of word, phrase and image prompts.
The Official Writer's Block Thread – Hey, its official.
The World Building Thinktank A re-make of the former world building game. This is particularly good for help with world building.
Non-Gaia Links:Rants:Limyaael's Fantasy Rants - Lots and lots and lots of rants about what not to do with a fantasy story. Extremely useful for those who write fantasy.
Websites/Forums:National Novel Writing Month - Nanowrimo forums, not only a great experience but they have a lot of helpful tips.
Writing.com – A particularly well known writing website.
Plotting/Brainstorming Techniques:The Snowflake Method An interesting and useful approach to writing a novel. Lots of helpful advice to be had here, even if you don't use everything that's covered.
Brainstorming Questions - Some basic questions which can help you set out and plan your story.
The note carding method – Yet another way to plot your story.
Its just a phase - The phase method for story plotting.
Writing.com Worksheet - A worksheet from writing.com to plan your story with.
Word Games and prompts:Writing Fix – A bunch of writing exercises, prompts, and games
Creative Writing Prompts - And more prompts
Hatch’s Plot Bank - And prompts
More writing prompts - And more prompts again!
Other
Terraformation: Making a Planet The Language Construction Kit - A simple guide to inventing your language