Back when we had our own business years ago, we had a stamper with our business name on it.  A lot of people nowadays have stampers for their own home use such as the invitationbox.com self-inking stamps.  Some prefer labels because of the cute designs, but stamps can have just as cute designs as the labels.  Either way, they are a big convenience when addressing just a few envelopes or a whole stack of cards or invitations.