I would be fine with not having one, but my Grandmother & Stepgrandmother have already started planning one for the family, and my friends are going to plan one as well. That said, they will both be ladies only. I feel a little uncomfortable about it given the expense that everyone coming is taking on, but I am just going to roll with it -- it's not exactly like I can say no!
Most of the time shower invites indicate what kind of shower it is - such as lingerie, kitchen, hour of the day, etc. If it doesn't it is safe to assume that you should purchase gifts from the registry (registry info is usually included in the invite). If you are close friends lingerie makes a nice gift as well.