How can I easily and individually update the Genre tag for a lot of songs? I am a DJ and I have just got a new Mac and transferred all my music to iTunes. A lot of my tunes do have the wrong Genre assigned mis-tagged (e.g.a tune that is TECH HOUSE is maybe tagged as genre House).

What I would love to be able to do very quickly is go through all my tunes and tag them genre-wise how I would like them.  I have so many  tunes that I actually ned to hear them before tagging.  My dream is to be in the 'music' section of my tunes, play a tune, have a little listen then hit a keyboard shortcut that would assign/change the genre to what I think it should be. 

At the moment, I listen, use a shortcut to get me to 'GET INFO' use the mouse to click in genre, delete it, then type in the new tag!
As a quick-fix you might just add the "Genre" field to the list of displayed columns (Cmd-J or right-click any column name) and edit the value there directly (double-click on the current value):



There are also applications available who try to clean song metadata automatically (e.g. Tagalicious) but they only work for "well-known" tracks and will probably not tag the genre the way you need it.