There are a number of programs online which you can use to create your own Coat of arms:
Has a good selection, the problem with it though is that the site can't add BTM's, so you have to use Zamzar to convert it to a JPG. Coat of Arms Creator: http://rpg.uplink.fi/heraldry/
BTM Converter: http://zamzar.com/
Easy to use, has a fair collection of ordinaries you can use. inkwellideas.