There's a warning bar across the top of every MSE page, warning me that the site is for discussion of the network, and that if I have a programming question I should take it to SO.
That sounds useful.
But it could do with a little fine-tuning. I suggest:
- don't display it on profile pages - you can't ask a question there
- likewise don't display it on a number of other pages (tag pages, user index, badges page etc)
- don't display it at all for users over X rep, where X is a value above the maximum reputation of people who ask off-topic questions here