The best performing site we ever had (uservoice) was for StackOverflow and they just had a red text at the top of the page that said something to the effect of

The best performing site we ever had (uservoice) was for StackOverflow and they just had a red text at the top of the page that said something to the effect of "Help us build the site" and linked to their uservoice forum. We also have a lot of people connect widgets to custom anchors (super easy).