The only thing I can suggest is for contributors to create a post on their blog or page on their website and at the end of every post include the link to it. If the person is well-known, doing an intro and posting a picture in #introduceyourself holding a steemit sign with the date is great. We won't usually forget they've "verified." For those who are a little lesser known, I suggest posting a public facebook post or twitter tweet and linking it at the bottom of their posts.

It's not a really good solution, but the only one we have at the moment.
Many times a person will "verify" the content belongs to them one time in the comments section of a post somewhere. I spend a lot of time reading back over posts to try to find if the content belongs to the person posting it.

Great question!