This article is from the rec.heraldry FAQ, by Gordon Findlay (firstname.lastname@example.org) and Francois Velde (email@example.com) with numerous contributions by others.
(An Ordinary is a reference book which lists shields of arms by the
charges they contain, which obviously helps identify an unknown shield.)
The SCA has one, but it covers only SCA heraldry. It is available by ftp
vela.acs.oakland.edu (18.104.22.168), /pub/heralds/armorials
nimbus.gp.cs.cmu.edu (22.214.171.124), /usr/kvs/pub
Other SCA armorials can be searched from the Web pages mentioned in question