I suggested in another thread that it would be nice if the campaign allowed for "channels" of discussion (and GM controls who can see what channel). Any old-school internet users who used IRC in a non-tabbed environment would know how this might work. Channels could be "In character", "Out of character", "Secret plot", etc.
The chat screen might then have entries like:
[IC] GM: The room begins to shake as the wizard completes his spell.
[OOC] Bob: I hope Mike doesn't freak out like last time!
[IC] Eldor looks for something to hold onto.
[IC] Thanan: I charge the wizard!
[SecretPlot] Seth takes the distraction as an opportunity to rifle through Eldor's pockets.
By default, anyone could create a channel, and the channel would have (by default) the creator and the GM as members. The GM can add/remove people to a channel, and can delegate this power to a player if needed. The GM could be removed from a channel if needed, but can add himself at any time - the channel is by default configured to broadcast additions/removals from the channel, but this can be disabled (unknown spies). The GM can always see a list of channels and members, and can choose whether players can see this information on a per-channel basis.
-- Pete.
Edit: Previous thread (originally about GMs snooping on player whispers) is <a href="http://community.roll20.net/discussion/2767/whispers-and-player-character-interaction" rel="nofollow">http://community.roll20.net/discussion/2767/whispers-and-player-character-interaction</a>