I remember one forum trying this a few years ago whereby all new members would be assigned to a member of the 'welcome team' who would do the opening PM thing, except they'd write a new one themselves (maybe they'd each send their own personalised one to their assigned new members), and be like a new buddy in the site.
I think for a bigger forum this could be interesting but a lot of sites aren't really big enough to make that viable.
I think for a bigger forum this could be interesting but a lot of sites aren't really big enough to make that viable.