I'm going over budget, and the budgeting tool here on WW is immensely helpful - however, at a glance I already feel there are "little" things missing that could add up quickly. Example: I didn't see anything in the budget tool for a guest book, which tends to be a staple item at weddings, and I've seen those often going for $50 or more.
The "invitations" section also wasn't very detailed (it just said "other stationery"... like what? Programs? Place cards? Escort cards? I added these in myself because otherwise I wouldn't have remembered what I included in "other stationery"... or I'll completely forget them until a week before.)
What have you come across in planning that you'd consider a "little" thing, that you may not have originally thought about in your budget?