The term selfie was first used in 2002 by an Australian man describing a photograph of a lip-injury while drunk at a 21st birthday: "Um, drunk at a mate's 21st, I tripped ofer [sic] and landed lip first (with front teeth coming a very close second) on a set of steps. I had a hole about 1 cm long right through my bottom lip. And sorry about the focus, it was a selfie."
Use of the "-ie" suffix makes sense in the context of Australian English, as they use it in creating slang words such as stubbies for a six-pack, rollie for a hand-rolled cigarette, pushie for a bicycle, and Aussie for Australian.
Despite Paris Hilton's brief effort to take credit for inventing selfies with her photos with Britney Spears from an event in 2006, Aussies seemed to be the genesis of this cultural phenomenon.