It doesn't do the PM notify business, but
I have a sticky menu with a couple of prominent colourful buttons right hand side, with Join and Info Site visible to visitors. It includes Twitter and Facebook links and a dropdown menu with site navigation. As the eye is drawn to the top right (the reason why drive on the left hand side in the UK), this is a good place to put your most important links as buttons.
The Sticky menu keeps these buttons visible all the time a visitor is browsing the site.
All based on good design principles, I think.

Javascript removes the Twitter and Facebook links when the menu becomes sticky. The buttons should become lighter on hover to fit in with my design, I think, not darker as currently. You can tailor make custom pages and links to these to suit the various user groups, to give each group the two most important links you want them to see.
You can grab the code off my site if you wish, or I can paste it into this topic if anyone is interested.
Site: http://opgo.co.uk/forum