I don't think it's fair to classify the clan system as "quaint" and "archaic" -- certainly the clan system is not what it used to be, a shadow of its former self, but it is certainly still very important to those who are members and/or identify with a particular clan. In some ways, thanks to the Diasopra and rapid communication, the Clan is more powerful than ever. Clans have changed with the times, much like everything else, but the intrinsic value of family is still there.

I'm also give to understand that since St. Andrew is the patron St. of Scotland it is a tartan that is open to any Scot.
Can't say I've ever seen this before in any tartan literature, but technically, any tartan -- with the exception of "restricted" tartans where permission must be obtained before the material can be woven, such as some clan and "royal" tartans. I know the "Earl of St. Andrews" tartan, orginally a Royal personage tartan, has now become an unofficial district tartan for St. Andrews, and some St. Andrew's Societies. The Royal Canadian Air Force tartan, btw, is based on the Anderson tartan.

http://www.pipeband.cfbtrenton.com/rcaftartan.html

http://www.regiments.org/tradition/tartans/rcaf.htm

Cheers,

T.