Now that you can play live poker with friends in other cities, trawl for cyberfish, or woo virtual girlfriends–all on your cellphone–calling someone seems almost passe. Mobile gaming is booming. The typical carrier already offers hundreds of downloadable games, and sales are expected to jump from $72 million (last year) to $430 million by 2009. With more than 140 million U.S. cellphone users, “the future of cellphone gaming is limitless,” says Levi Buchanan of IGN Wireless, an online gaming portal.

Classics such as PacMan and Tetris–which has sold more than one million copies since 2002–are popular, but today’s cellphones aren’t limited to simple videogames. The most exciting new games capitalize on what differentiates cellphones from other portable gaming gizmos: They let you to talk to or text-message other players midgame; require that you snap photos of real-world objects with your built-in camera; and, in some cases, use GPS to incorporate your actual movements into the game. Of course, there are downsides to gaming on your phone. Keypads are ill-suited to car chases or dragon hunts; unlike console game controllers, most phones can register input from only one key at a time, so you can’t simultaneously kick and jump, for instance. Puny screen size can also be a bummer, but new 3-D graphics chips from Santa Clara, Californiaâ€based nVidia will squeeze more detail into those tiny spaces. “We’re past the novelty stage,” Buchanan says. “We’re already starting to get into Game Boy territory.”

Below, a look at the capabilities that make your phone an ideal console for games on the go.