SpyBot - Search & Destroy - A free program for removing spyware/adware/malware/etc
Bitdefender - Excellent Anti-Virus software (and free!)
Fuelly - A site that lets you track, share, and compare your fuel efficiency.
Browser Shots - A very useful site for web designers to check compatibility with different browsers on different operating systems.
Adafruit Industries - An excellent source for hobby electronics like Arduino and Raspberry Pi.
Digistump - The home of the Digispark; a very cool tiny Arduino-compatible development board. Also several other neat products.