Excerpts from Wikipedia:

Joseph Hahn, better known as Mr. Hahn, (born March 15, 1977 in Dallas, Texas) is a Korean American turntablist and director best known as the DJ for Linkin Park.

Joe joined Linkin Park, after meeting fellow band mate Mike Shinoda in art school, when the band was called Xero in 1996 as the band's turntablist.

[poster's comment: Xero sounds like a nu-metal themed special edition of an Aero bar]

On the 2007 album Minutes to Midnight, Joe Hahn focused his contributions on programming with his sound effects board and MIDI keyboard.

[poster's comment: Mr Hahn is very good at his MIDI keyboard, and has his grade 6 in MIDI keyboard]

A proficient music video director, Joe has directed videos not only for his band Linkin Park, but he has also directed videos for Static-X, Story of the Year, Xzibit, X-Ecutioners and Alkaline Trio.

[poster's comment: washed out colours, quick edits, bands playing in crumbling brickwork buildings, camera shakes when vocalist screams]

In 2005, Hahn opened a retail concept store and brand Suru, located on the famous Melrose Avenue in Los Angeles.

[poster's comment: hopefully the concept is nu-metal. dude can't get a pair of jeans that hang 'round his ass for SHIT on melrose av since 2002]

He was also the one to advise the band to put the single "What I've Done" on the soundtrack for the Transformers live action movie.

[poster's comment: I might just go round suggesting stuff to people, and if it happens I can have it put on my wikipedia page to pad it out.]