A list of the various suppliers, websites, etc that I find useful.  To be clear, none of these businesses pay, or induce me to endorse them, or their products.

Electronics

• Adafruit – http://www.adafruit.com/
  I have made a number of purchases from Adafruit over the years.  Good service, prompt delivery, good quality products, and helpful staff when I had a delivery issue.  Highly recommended for micro controller projects like Raspberry Pi, Arduino etc.  They also have excellent periferals, tutorials and heaps more.
• Jaycar – http://jaycar.com.au
  If you are in Australia and you need electronics components fast and can’t wait for them in the post, then Jaycar are pretty good.  They don’t have everything and aren’t always the cheapest, but they are a pretty good option with lots of stores.
• Fritzing – http://fritzing.org/

Design & engineering

• Simscale – https://www.simscale.com/
  For truly awesome finite element analysis, theromdynamics, and fluid dynamics.  All in your web browser from your own 3D models.  I hope to make a lot of use of these guys