According to the trusty folks over at Entertainment Weekly, The CW is currently "edging close to a pilot order" for a series based on the character.  Green Arrow is the alter ego of Star City's resident billionaire Oliver Queen, a man gifted with his bow, slinging arrows frequently tricked out with all sorts of technological flourishes.  Unlike many other heroes ,Queen has an active, sometimes radical, political conscience, and no bones about speaking his mind.

The character, a frequent Justice League member, was created by Mort Weisinger and George Papp in 1941.

Developing the would-be television series are Greg Berlanti, Marc Guggenheim, and Andrew Kreisberg.  Both Berlanti and Guggenheim contributed to the screenplay for last summer's Green Lantern, and both are television veterans who worked on Eli Stone with Kreisberg.  The latter has served as a co-executive producer on Warehouse 13, The Vampire Diaries, and Fringe.

On Smallville, the ten-season Superman-centric series, the character was played by Justin Hartley over more than seventy episodes, first as a recurring guest, then as a regular castmember.  If this Green Arrow goes to pilot, it won't be Harltey playing Oliver Queen, though, as this series would apparently be divorced from the elaborate Smallvile continuity.

Also currently in development as possible series are DC characters Deadman and The Spectre.  While Green Arrow isn't a household name, he's certainly a more recognizable figure than either of those supernatural figures.  Not that familiarity ensures an actual series; last year, the much-derided Wonder Woman pilot never made it to air at NBC, and has presumably been locked away in a vault where we'll never see it.