The link on Advaita philosophy seems to be good. Has a good explanation of Dakshinamurthy Astakam and its explanation of Advaita. Donot miss the four fundamental Mahavakyas part. I have also added a link to the sidebar.
The following is the common line from the astakam:
Tasmi Shri Gurumurthaye Nama Idam Shri Dakshinamurthaye!
of course we know: Sivaya Gurave namah.
Postscript added on 06/23/05: Dakshninamurthy Stotram and Astakam are the same. Written by Shri AdiShankara. have the common 4th line "Tasmay Shri Gurumurhyaye, Nama Idam Shri Dakshninamurthaye".