There are a boatload of Aussie's abroad, but it's hard to say if any of them would be superior to local options (see Wallabies Player Exodus thread).
John Porch as someone mention is over in Connacht and is playing some nice rugby as is Jarrad Butler (who is also there), but unlikely better than local options. Andy Friend did like to pull in an Aussie to fill his roster.
The number of players in Japan is huge, but most are known qualities;
Division One: Quade Cooper (Hanazono Kintetsu Liners), Will Genia (Hanazono Kintetsu Liners), Samu Kerevi (Tokyo Suntory Sungoliath), Sean McMahon (Tokyo Suntory Sungoliath), Bernard Foley (Kubota Spears, Funabashi, TOKYO-BAY), Nick Phipps (NEC Green Rockets Tokatsu), Taqele Naiyaravoro (NEC Green Rockets Tokatsu), Matt To'omua (Mitsubishi Heavy Industries Sagamihira Dynaboars), Isi Naisarani (Shizuoka Blue Revs), Marika Koroibete (Saitama Panasonic Wild Knights)
Division Two: Tom Banks (MIE Honda Heat), Rory Arnold (Hino Red Dolphins), Liam Gill (Urayasu D-Rocks), Israel Folau (Urayasu D-Rocks).
... and the ones that would have been leftfield options in Japan has already beat us to the punch and capped. Players like Jack Cornelsen, Ben Gunter, and Dylan Riley. Dylan in particular I have been real impressed with, would have loved someone to have brought him home.