In Phi Mu (at least my chapter) we do what most have already mentioned...circling around the bride and singing. There is also a Chapter Development we do while undergrads which includes an activity geared towards your wedding but I don't know that I am allowed to disclose it...any other Phi Mus know what I'm talking about?
By the time I get married...if I ever do...I will probably miss out on the singing thing due to losing touch with sisters and such but there are other facets of Phi Mu that will definitely be present!