Many of the gadgets that people carry around are really variations on the same idea: They make activities that used to require staying in one place more portable. Cell phones let people take calls everywhere. MP3 players can store an entire CD collection in a handy device about the size of a deck of cards. With PDAs, smart phones and laptops, people have constant access to e-mail, calendars and organizers.

Photo courtesy RIM A man using a BlackBerry

People can also use laptops and handheld devices to create documents on the go. But until recently, printing those documents could be tricky. Handheld devices, with their scaled-down operating systems, don't always have built-in printing capabilities. Laptops can print, but only if the user can find a printer, connect to it and install the right driver. The other alternative -- saving a document to disk and visiting a copy shop -- isn't always convenient. It also isn't possible for devices that don't have disc or CD-R drives.

Fortunately, there are several options for printing on the go. They include everything from portable printers to services that let people e-mail documents to fax machines. In this article, we'll take a look at the methods for mobile printing, including what to keep in mind when choosing software or services.