One of the most important Firefox plugins I use on the PC is Adblock Plus. Not only does it significantly reduce the blinking and flashing of overly obtrusive advertisement on web pages but it also accelerates download times. On mobile web browsers, however, a similarly easy to use functionality seems to be still a bit away.
For the iPhone, it looks like there are some programs available but only with a jailbreak. On Android some experimental software seems to exist and there is an app on Android market but it requires the user to change proxy settings manually.
Opera Mini on my phones automatically loads the mobile version of many of my favorite pages which have reduced advertising. A creative way to reduce over-obtrusive advertisement.
So what I am still missing is an easy to install add-on just like on the PC. It's about time, even if Google and Apple don't like it. But maybe I am overlooking something, so as always, feedback is welcome!
How about Windows Mobile, Maemo, the Palm Pre and other platforms?