This was love at first sight: probably the ad-blocking solution I've been looking for. It's basically the good old hostfile-based approach, but with a nice, appealing interface. Plus, it works out of the box because has a list of known ad-servers from www.mvps.org... I'm totally convinced. Promise not to uninstall. ;)
1) use the Tear browser 2) install advoid 3) disable javascript whenever possible 4) now you don't need a N900, your N8x0 is fast enough :-)