May be a silly question, but I'll give it a shot :).
On my forum app I would like to allow users with sufficiently high reputation display links to their home pages under every post - without the nofollow attribute (while lower rep users will have the nofollow)
I am happy to help the site contributors improve rankings of their own, but not sure if this can actually deteriorate the rank of the host (the site that hosts those links) - as potentially the same link to the user's home page may be peppered in the pages of the host.
What do you think? Thanks.