There are a lot of theatre sites and blogs I visit, but these are the highlights:
The often hilarious West End Whingers -
http://westendwhingers.wordpress.com/The Australian based Theatre Notes provides remarkably in depth coverage of productions -
http://theatrenotes.blogspot.com/The Scottish Theatre Forum is a great community for those involved in all aspects of Scottish Theatre - performers, companies, professional & amateur, and those who just enjoy theatre (a bit busy at the moment with their own production of "We Will Rock You" in Glenrothes this week)-
www.scottishtheatreforum.comAnd I guess I should mention my own review site, based around Glasgow but also covering Edinburgh Festival stuff. I can't pretend it's in any way academic but we see a lot of theatre and provide a genuine, if often emotional based, response to what we see.
http://www.viewfromthestalls.co.uk/