Online Video showing how to simulate a Gradient ND filter in Photoshop
 

This one is working so well for me - I thought I'd promote the guys podcast by posting up a link to this tutorial

http://www.thedigitalphotographyconn...ayer.php?ID=58

ignore the boring bit for first 1/3rd - and how Americanised it is - but the last 2/3s is cracking

Mark.