While the issue of whether technology makes our writing lives easier is up for debate (when your motherboard departs this world and takes with it several months of work, you will understand), there is a lot of great free, or almost free, technology out there to help writers. I wanted to use this post as a chance to compile a list of helpful resources.
Editing and Writing
AutoCrit - The AutoCrit Editing Wizard is an instant book editor that helps identify problems (word echoes, grammar, etc.) in work you upload. There is a limited free version. The more functional versions require an annual fee.
yWriter - Free writing software for writers made by writers (in the spirit of full disclosure, I am a Scrivener devotee, but my friend Karen loves yWriter - she says it is better than Girl Scout cookies - mighty high praise).
Elements of Style - No, you didn't escape this when you left your formal education behind. It is available online so your high school English teacher doesn't cringe when she reads your masterpiece.
Motivation and Creativity
Dr. Wicked's Write or Die - Southern Magic goddesses Jennifer Echols and Naima Simone extol the virtues of this motivational tool that punishes its users with horrible noises, blood dripping from the screen and the munching of written words if you stop writing for too long. The online version is free, but there is a cheap download that you can use when you are sans internet. I LOVE Write or Die. This is a NaNoWriMo must.
Written? Kitten! - Yes, I am the crazy cat lady, so this works well for me. This tool gives you a blank page where you can type. Every time you cross a milestone (100, 200, 500 and 1000-word settings are available), you are rewarded with a warm fuzzy kitten picture. Awwwwww :)
XMind - This is a free brainstorming tool that is easy to install and use.
One Word - One word writing prompts.
The Emotion Thesaurus - I joke that my characters must be perpetually dizzy and have reflux issues based on the way I describe emotions. I have saved these poor souls from tortured futures by using this site to better describe their emotions.
Wallwisher.com - This is a digital version of 3X5 cards. Use it to layout your story and plot lines. It is great for collaborating on stories and planning write-ins.
Blake Snyder's Save the Cat Beat Sheet - Several Southern Magic members (even the pantsers) swear by the Save the Cat method and the beat sheet for plotting a story.
National Geographic's What's in a Surname - This is a fun tool to identify common surnames in the geographic area of the US where you story is set.
University of Wisconsin's Dictionary of Regional English - This helps ou keep your dialogue authentic. It places words and phrases in times and locations.
Google Earth - A must if you are setting your story in an area you don't live.
This list is just a start. Please post your favorite resources in the comments. I'll edit and modify this post in a few days so you can bookmark it and have it available for future writing needs.