different div shapes (circle, star, oval, etc.)

Animation

• rotating platter
• element along a circle

Limit the animations to scale, position, opacity, rotation and things are fast, as explained here.

http://net.tutsplus.com/tutorials/html-css-techniques/say-hello-to-css3-filters/

http://html5-demos.appspot.com/static/css/filters/index.html

• Loading correct image for retina display (see tip 1 and using @media)
• making sites printer friendly with css
• using @import to make site mobile friendly

Fading in and out:

• tryit editor
• play with cubic bezier for fadein/fadout

Page transitions:

• examples and source (appears to use jquery)

Page turns

• css3 only
• tutorial (same tutorial?)

Catch unused css:

• Chrome has an audit tool. Run the audit and it will report the unused css
• https://github.com/giakki/uncss ← removed unused css from your css files. Looks excellent!