Making pixel art is like writing kids' books: Shockingly nuanced, and way harder than it looks. But pixel art site Lospec has collected a gobsmacking 566 tutorials on how to draw at micro-size. Each tutorial is tagged and categorised by medium (such as videos or slideshows). To get specific tips and lessons, search tags like sprites, dithering, texture, or trees.
Graphic: cure (Pixel Joint Forum)
If you're new to this, begin with Lospec's own introduction, "Pixel Art: Where to Start." It will give you a few tutorials and a canvas to play on, then point you to some tools and communities.
Even if you absolutely don't have time to learn pixel art, you might like to waste an hour gazing at all the pretty art and nodding sagely at the techniques in the tutorials.
Pixel Art Tutorials [Lospec]