The little printer box that the places you visit should have
Although some airlines provide electronic boarding passes that can be scanned from your smartphone, not all do. But you can't print the boarding pass at the hotel's business center, because its printers require a PC, so you end up doing it at the airport. Printing agendas and maps when on the road can also be handy, but with a tablet or smartphone, you can't.
Road warriors should lobby the business centers at hotels and conference centers and the lobbies at companies whose offices they visit to install a simple device on their networks: Lantronix's xPrintServer. It lets any iOS device print to any printer on the network. There are three models: small office/department, home, and large office.