This site offers a gallery of alternative Dalek designs, and it also hosts the witty and excellent online comic Second Empire. Well worth checking out.
Steve Redfearn's website was one of the original inspirations for my work. His Dalek renders are as good as it gets. Sadly his site is no longer available, but you can still see some of his work in the Dalek Links gallery.
Peter Labrow's site is the place to go to find links to other Dalek-related sites.
This site provides a wonderfully detailed record of the actual Dalek props used in Doctor Who, and how and when they were modified. I've found it to be an invaluable aid.