How do you skirt the wedding gift issue without sounding smug?

We do not want gifts. Really. Guests can give what they want to give but we have no expectation of anything from them. We keep getting asked where we are registered, what things we want/need and I don't know how to say we just want them to come and celebrate with us without sounding so smug. Particularly, my fiance's mom mentions things people can do for us in lieu of gifts (photos, cleanup, etc;) but I do not feel I can ask for these things because we do not expect anything in the first place. We're not particularly well off or anything, sure there are things we want but we do not want to come across as greedy. Our wedding is about celebration, not gifts.