Yep that the Panditji's website. I've had the honor of meeting him and his son Rahul ji a couple of times when they've been touring. Both are outstanding musicians and were very generous with their time in sharing with others about the instrument. I can't say enough positive things about both of these men.
IMHO, the santoor.com is the most useful site in terms if you are trying learn santoor. In addition to the general history of the instrument (from the Indian point of view), there is a tuning and string chart, an extremely useful explaination of musical terms and links to at least one tutor.
Pandit Nandkishor Muley is a senior student of Pandit Sharmaji and is an excellent music and teacher in his own right. I think they maybe out of print but he made a couple of recordings for HMV that were truly brillant, and well worth finding.
Another student of Pt. Sharmaji is Shri Kirpal Singh Deoora ji, who lived in the U.K.. He teaches and has made some fine recordings of remarkable depth. He is also a master of the Indian drums the tabla. On his site you can listen to large chucks of him playing Ragas Todi and Bhairavi free!! His site is www.kiranpalsingh.com/ if it isn't posted elsewhere on the forum.
Anyone seriously interested in learning about this music who hasn't a teacher around to help should get ahold a copy of "The Classical Music of North Indian" by (Ustad) Ali Akbar Khan and George Ruckert. It not only explains how Hindustani music works in theory, it gives you actual compositions and exercises to learn and play. There are now a number of online tutors that can help too.