Mockupea - Mockupea is an online tool for creating 3d book mockups with a lot of features.
DOOM Captcha - Captchas don't have to be boring
Stackoverflow '90s - Bring back '90s to Stackoverflow with this extension
reCAPTCHA - reCAPTCHA is a free security service that protects your websites from spam and abuse.
Box Shadow Generator - Generating CSS3 multilayer box-shadow has never been easier.
Squat Captcha - The worst captcha ever! Forces you to do 10 squats