Pretty amazing what shapes can be made with CSS, http://css-tricks.com/examples/ShapesOfCSS/
@Firstmate Yes, I get a lot of these from there. Very good source of information.
This is quite an impressive list =P. I kinda like the technique used for the space invader - it's like a pixel-by-pixel rendition.
As far as border shapes go, some interesting effects can be created by using different border styles than solid. Here's something I've come up with to demonstrate: (Currently only contains hourglasses, but I'll be adding more) http://dabblet.com/gist/2816698
Lol a few towards the bottom are pretty neat.