I used to browse the Web with Opera Mini, which was a J2ME midlet, on feature phones such as Motorola C651 and Nokia 6230i :) It worked by rendering the full blown site server-side and sending it back in a simplified format for the phone to display, which worked much better than bundled browsers which weren't very useful for much more than WML or XHTML-MP. I have also chatted with people via XMPP extensively thanks to Bombus (remember when Google Talk was a fine, open and federated XMPP implementation and pretty much everyone was reachable there? Those were the times...).

Smartphones such as Symbian ones already had more usable native browsers though.