For info on what sites are available, what level mage of what path are needed to search for them, as well as what they do, check out Sunray's compilation of Magic Sites.
Here is a link to the same document on Arry's site,
http://www.bl23c.com/arryn/downloads/dom2sites.xls
(I would give you the direct link to Sunray's site, but it is either down at the moment or I am having trouble connecting to it.)
I believe the info is largely based on Dom1, where items in Red had changed or were added in Dom2. Enjoy.
-Gateway103