What about the coat of arms (or a more simpler "one color version") as a personal seal? I just like too much the work of the CoA people, I could love that kind of ideas.
I've seen others suggest that instead of the Founder or Benefactor symbol on pledge reward tiers, they would prefer to have their own crest. If your crest was treated as a decal, and these items could have decal applied, that might work. Same with your crest being a seal on an envelope.