Forum OpenACS Improvement Proposals (TIPs): Re: Tip # 73: Enable to Hide/Show User Email
If you feel like getting deeper than a simple site wide on/off form option for email implement it in a way that allows levels of permission on the entire profile: e.g. I want my friends (and friends of friends) to see my entire profile (email included), but registered users and non-registered users to only see X,Y, and Z (with contact option over email limited to the form). For an example of different levels of view permission from a web based social networking site see orkut.com (which has permission level of profile based on relationship to user: friend, friend of a friend, strangers).
Now to make it even more interesting: with roles and different kinds of groups made possible by OpenACS it gets fun quickly (hypothetical example from .LRN: multifaceted student X wants to share certain parts of her profile with the pink commie hyper-liberal dissenter political student "club" she attends on Tuesdays and other parts of her profile with the young neo-conservative republican group she frequents Thursdays).