Moo.com has new stickers and they're perfect for wedding swag! Screw calligraphy! Wouldn't these rectangular stickers make for hot wedding invitation mailers?
Or great for your return address on RSVP cards?
They also have these neat sticker books that are great for all kinds of wedding related things: seal invitations and thank you cards, use them to differentiate your place cards, and some folks have even used them as wedding favors. And since you can upload your own photos and logos they're can be as personal as you want them to be!
Of course they also have ready-made stickers for those who don't have the time to devote to customizing everything.
For even more ideas and inspiration head over to Moo.com and see what you can come up with.