Programming

Unofficial Windows Binaries for Python Extension Packages
For those times when one must use Windows.
The Robot Operating System (ROS)
A framework for writing robot software.
CheckiO
A game for coders.
GitHub
A great place to host your Git repositories.

Web Development

Bootstrap
Free and open source front-end framework and set of tools for creating websites and web applications.
Syntactically Awesome Stylesheets (Sass)
A very useful extenstion to CSS.

Robots

Jetson Hacks
For anyone using the Nvidia Jetson dev board on their robotics projects.
The Robot Operating System (ROS)
A framework for writing robot software.
IEEE Spectrum Robotics
For all of your robotics news.