I have plans to make a credits plugin, where skins and plugins will add the neccessary credits to an array inside the credits plugin, and then the skin will display it in the footer or wherever.
BUT, it seems that there have been plans to do this already;
http://forums.b2evolution.net//viewtopic.php?p=39806#39806
I have all the code already for the Credits plugin, i just need to turn it into a plugin.