WordPress.org is web software you can use to create a beautiful website or blog. They like to say that WordPress is both free and priceless at the same time.
This is the biggie of course. We use WordPress alldayeveryday. As of a couple months ago it was reported that 26% of every website in the world is powered by WordPress. This is the tool that we build all of our websites on. We have written a separate post on WHY we love WordPress so much, but basically this is our daily grind: WordPress.