This might have been suggested before, but what I would sometimes find useful is a sort of 'recommend post' function. Where you can recommend a post to a particular user, much like we can now notify moderators of specific posts.
I'm sure not everybody reads absolutely everything on this board, and it could come in handy to be able to recommend a specific post to a specific user - especially when the interesting post is buried in a thread that the user in question would not normally read.
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Ænigma.

COS Folding @Home Team
Des Duivels (on Satanism in Dutch)
Des Duivels Forum (Satanic forum in Dutch)
Temple of the Vampire

Kindly leave your morals at the wardrobe.