Webcrastination 

The act of wasting enormous amounts of time aimlessly browsing the internet when one should be completing other, much more important tasks. It usually starts as a simple search or the checking of one's emails, and can last for multiple hours before the individual realizes it.

Most prevalent in college students.

This definition is on Urban Dictionary thanks to webcrastination.

Webcrastination by Pilotguy44 October 14, 2009

webcrastinator

n. one who procrastinates through the internet; one who spends all their free time on the internet; one who never gets anything done because they are constantly on the computer

Jean is such a webcrastinator, she hardly ever leaves her computer desk.

webcrastinator by kristina-bree October 7, 2009