I think it will be nice if we will have some kind of verification of Bitcoin address for user.
I can do it in this way:
in profile I can add link in right of Bitcoin Address [verification], this link will point to page with 2 regions:
[vefication message] - some text with random hash
[form] - form for enter signature of this hash, after sign it with private key of you Bitcoin Address.
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Same mechanism I think can be used to create PGP keys. But for PGP I will send only encripted email for hash verification.
ETA : 2 weeks, if it is interesting to someone .