Ok so basically I used the file from

http://www.mvps.org/winhelp2002/hosts.txt

Essentially this file contains a bunch of ad site names and overrides the normal lookup of their IP - pointing them at localhost instead. So here is what you do.

Grab this attachment. unzip it somewhere. backup your N900's current hosts file. copy this hosts file to /etc/hosts on your N900.

Thats about it. Works well for me but I make no guarantees about yours etc.