1. Five Interface Laws by Kevin Hale

Great presentation on interface laws. I remember watching this presentation a few years ago and it left an impression on how I try to design products:

2. Color Science

I would always wonder why certain colors looked so good together. Here's a great explanation on color science:

There is definitely a science. However, there are usually many correct options, so there is also a subjective element too, which is what makes design so awesome. Different designs call for different colors and styles, however, in all good designs there are always a few common denominators:
— via Colm Tuite, Is there a science to picking colors that work well together or is it just subjective?

3. Never Use Black

A great explanation as to why you probably don’t want color: black. This is a simple concept in theory but makes a disproportionately large impact.

Problem is, we see dark things and assume they are black things. When, in reality, it’s very hard to find something that is pure black. Roads aren’t black. Your office chair isn’t black. The sidebar in Sparrow isn’t black. Words on web pages aren’t black.

— via Ian Storm Taylor, Never Use Black