Turn off the image loading in Opera and you're a long way already
I read the Palm version of Slashdot most days through GPRS, and one day's worth of /. takes only about 50-100k. I keep images off (or only already retrieved images) too, just in case I go off-site following the occasional link. And I use privoxy as well, to be sure. And I keep a browser window with gmail permanently up and running (it doesn't matter if you change network between wi-fi or bt now and then), this makes it possible to check mail with only a few tens of kbytes as well. All very useful when using GPRS without a data plan (i.e. I have to pay as I go). And it makes GPRS fast enough too..