Standardista (Estelle Weyl) deserves a useful links post devoted only to her blog.
First there’s a wonderful beginning tutorial on the canvas element: HTML5: Introduction to <canvas>. As a bonus, she explains the difference between canvas and SVG in a clear and succinct paragraph at the end.
In a page of example gradients called Striped Gradients, she shows some really amazing things that can be done with pure CSS 3, no images. Best of all, the styles are all in the <head> so you can take a look at how she did these eye-popping things.