We use several My Pages, as entrance to different family information, interviews, references, ect. For example page "Virtual Cemetry" is collection of pictures of tombstones with links to person's profile. Any Family Page is the collection of interviews, documents, events of this family.
I actually have been wondering the same thing . . .
I have three trees that I manage but the "My Pages" option appears only within one of the trees. Also I would like to use the Links, Polls, Events and Forums options but do not understand how to use use them.