As an aside to my discussion with Baza, I had a go at using Google to measure the use of names for the site. It's a primitive test, but interesting anyway. I used the Advanced Search method and put each name into all three of the top boxes. Here's what I got:

Callanish 17,100 pages
Calanais 6,310 pages
Classernis 4 pages
Fir Bhreig 3 pages

Obviously the stats for 'Callanish' are tilted by the use of the name for other nearby sites. By running the same search but excluding the characters I, V and X the name Callanish gets 9,840 pages listed on Google.

Also of interest to anyone who is into this sort of discussion is Burl's British Archaeology article:

http://www.britarch.ac.uk/ba/ba17/ba17int.html

K x