I have a few different ways I process my email inbox, depending on whether I'm at home on my Mac or away and on my iPhone or iPad.

At home, I go through each message and decide if it is "reference" or "actionable." If reference, I move it into Evernote and if actionable, I move it into Omnifocus. I do this extremely fast using apple scripts provided at Veritrope.com and it's just Command + E for Evernote and Command + O for Omnifocus. The applescript lets me choose which Evernote notebook the message goes into and even add tags. I process the Omnifocus inbox when I have time, already knowing these are actionable items and need to go into specific contexts.

Away from my Mac, I forward reference emails using my Evernote email address and my actionable tasks using the Omnifocus email service (in beta but works great!.)

All of the original emails are then archived in Gmail and I hit archive immediately after forwarding the message. if I do not do this step, I end up forwarding the same email multiple times because I cannot remember if I've processed it or not.