Use the space bar in the BB browser to move down a page at a time, shift-spacebar to move up a page at a time.
In Opera Mini, press the 2 key to move up a page at a time and press either the 8 key or the space key to move down a page at a time.
Also, if you go to a thread click on the >> symbol to the right of the page #s on the post to take you to the last post, if it's a long thread, it's probably easier to go to the last post and page up to read recent posts.
Posted from my CrackBerry at wapforums.crackberry.com
