Well, I have heard of few cases that have some minor relation to the BG moding... such as K'aeloree finding employment
, horred the plague(Big Picture mod current coder) involvement in The Shadow Sun
and whole a lot of modders helping in the EE, not that they were payed, but they got their feet wet.
Also there's a few things, like me making a mod or two to advance the cause (well a SHSforums websites paypal donation), I of course did it for free and the donation suggestion was originated by the mod requester. So no money was passed to me.
The website admins can get a small amount of revenue by adding online ads to their sites, and have paypal etc. to increase income, but I have a real doubt that they can make any real money out of that as they are more likely be pouring a lot of money to have the sites at all, and not being subject to spam.
And of course there was the one sad and old case of the blackwyrmlair's forums exclusion to paying users, which was then reverted back in the recent times.