It seems that a lot of people have been having trouble eliminating ads recently. Here is how I am almost pretty sure I got rid of most ads!
Open up the Market, hit the menu button, choose "Settings," and un-select the "Receive interest-based ads."
In conjunction with the free "AdFree Android" app (which requires root access), this should eliminate a majority of the ads that are pestering you, it has at least worked out pretty well for me so far.
That's it! Hopefully this works for you!
Also not that after you flash a new ROM, you will have to go back in and disable it once again.