There was also a great /etc/hosts file that I got for my N900 somwhere on these forums a while back.

It basically took a HUGE list of some of the worst web page banner ad domains and equated them with 127.0.0.1.

Worked like a charm on both my Linux desktop and my N900. Would be a good fit for any N9 owner looking to avoid ads since it would apply to all browsers on the phone and not just the buggy mobile Firefox.

If you're interested and can't find it with the powersearch, let me know and I can extract it from my old phone when I get home.