What do you reckon could be added to DiS?

I've thought of this one recently as someone has wanted to ask something within a thread to a particular user. Why don't they put something in like on facebook where you can 'tag' a person in your status to get their attention. So, here in a thread I might want to find out about mars bars half way through a 'what's your favourite chocolate bar thread'

eg

I love bars bars, but they're quite fattening right? Or don't they give you loads of energy? @marcofella?

And then the user gets a message saying they've been 'tagged' in a thread.

I know it's not a good idea to veer off toward the current social media and keep it more forumy, but I like this idea.

Any others?