Tool to make reading a forum easier
That would depend on the specific forum software, and would be better asked in uh 'super user' or one of the other stack exchanges relating to internet or computer use.
Play by Post (Roleplaying in a Forum)
The best forum to roleplay in that I have found is mythweavers.com. It has a forum software that allows each game to have a miniforum of it's own with multiple threads or categories of threads.
Additionally, too many players and/or GMs in the same thread makes it nigh impossible to have any sort of storytelling, or even like, a conversation in-character. Same with real life, really. Multiple threads help with this. But ultimately organizational issues make 'too large' games slow down and suck in any case.
Real-Time Geographically Displaced Online Roleplaying (RTGDOR - Roleplaying somewhere else)
roll20.net provides an interactive tabletop for combat, and IRC (Internet Relay Chat) is a traditional medium for online roleplaying with a bot like Bones to provide dice-rolling capability.
Skype video chat is another good online tool for roleplaying.
Ultimately any communication tool can be used for roleplaying, with some limitations based almost solely on dice-rolling. Which you use is a matter of preference and the specific type of group you have. Play by Post (forums) is great if people can't get together at a specific time - some form of real-time chat is nearly always superior otherwise.