Deadline week starts today for me (as well as all you NaNoWriMo'ers out there), so to help you get some writing done while you're online, here are:
Ten Things for the Online Writing
The Bonsai Story Generator takes the text you cut and paste, turns it inside out and upside down, and gives you some new word combos, lines and all kinds of ideas.
The Cut Up Machine over at Language is a Virus takes whatever text you feed it, chops it up, rearranges it and generates new text.
Google Docs allows you to create and edit documents online with their simple word processor; if you're looking for online storage they offer free and low-cost accounts as well (I use and personally recommend this one.)
iNetword is going bye-bye in March 2012, but until then you can use it online for free.
Also at Language is a Virus, the Sentence Builder can give you a hand with line construction.
SpringNote is a free online notebook based on wiki.
Think Free Online Office provides 1 GB of free storage along with online document viewing, editing and collaboration.
Write 100 words at Written? Kitten and an adorable kitten pic pops up as your reward.
Zoho Writer is "an online word processor that allows you to create and share documents online. You need not install any software in your desktop, all you need is just a browser and an internet connection for working with Zoho Writer."
Zoho also has a virtual notebook in beta here.