An online Heraldry generator, "Create-a-shield":

http://www.karlwilcox.com/?page=shield

An example pasted into the blazon field:

Gules, on a bend or between two escallops argent a Cornish chough proper between as many cinquefoils azure; and on a chief of the second a rose of the first seeded gold and barbed vert between two fleur-de-lis of the field: for Petre
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(It also has a nifty "random" button)

-Rob A>