Think is a social that only you or immortals snooping you can see. It can help support your actions from a roleplay standpoint on the spur of the moment.

syntax: think (message)
what immortals would see: X thinks: (message)

This has been taken up before. I think the official answer was to use tell 'self' 'what you think'.

But I agree, it would be a nice addition. And im sure it isnt to hard to code.