http://www.medic.mie-u.ac.jp/derma/anatomy.html
This site has a very clear color micrograph of a skin section with clickable areas for more details. The site includes links to other dermatology pages.

http://www-sci.lib.uci.edu/~martindale/Medical.html#Derm
Links to many good dermatology sites.

http://www.maui.net/~southsky/introto.html
A very useful page for skin cancer information. There are a number of links and detailed explanations.

http://www.pinch.com/skin/
This is a page with links to several skin disease pages including a search link.

http://www.hkma.com.hk/std/menuskin.htm
Very detailed information about different types of eczema