I like jwfact's http://www.jwfacts.com/watchtower/cross-or-stake.php
It would probably be interesting to add the information found in this article:
http://www.biblicalarchaeology.org/daily/biblical-topics/crucifixion/the-staurogram/
If someone wants to contact the professor who wrote the article, and who would, of course, be the authority on the subject, you can visit his blog at:
http://larryhurtado.wordpress.com/2011/10/13/the-staurogram-correcting-errors/
What is interesting, and I don't know why there has been so little attention given to this, is that the Staurogram appears in the actual Bible Manuscripts!!
P45, P66, P75.
From http://en.wikipedia.org/wiki/Christian_symbolism#Staurogram:
The Staurogram was first used to abbreviate the Greek word for cross in very early New Testament manuscripts such as P66 , P45 and P75 , almost like a nomina sacra . [14]
The fact that the WTS knew about the Nomina Sacra is that there is a reference to them in the WT 1957 July 1, page 394. When they were doing the NWT, they must have come across this.
From the NWT's manuscript and versions list:
P45 Papyrus Chester Beatty 1, Gr., third cent. C.E., Dublin, G.S.
P66 Papyrus Bodmer 2, Gr., c. 200 C.E., Geneva, G.S.
P75 Papyrus Bodmer 14, 15, Gr., c. 200 C.E., Geneva, G.S.
This is significant because it pushes back the first art depictions of the cross to the second century CE. Not only that, but the Staurogram appears on Bible manuscripts themselves!!
ILTTATT