Rui CarmoThe Doris Browser is (without much question) the best all-around HTML browser for Series 60 phones.
Unlike the bloated Opera port, this takes up less than 200KB on my 7650, which means you can actually use the phone for something else. It supports JPEG, GIF and PNG images, image maps, GZIP content compression, SSL connections and basic HTTP authentication (plus cookies). And all of this without any sort of proprietary proxies.
Initial impressions over GPRS are excellent - sites with GZIP compression (like this one) load extremely quickly. It can also connect to the net via Bluetooth if you tweak your PC configuration a bit.