You can click on a point on a map and use that as an Action Filter for another sheet on a dashboard. See - Filter Actions
You may also just be able to get away with a standard tooltip - http://onlinehelp.tableau.com/current/pro/online/windows/en-us/help.htm#viewparts_marks_markproperties_tooltip.html
Thanks- I'll look into the filter actions.
I don't quite like the look of the tooltip but I think you're right and I can use that if need be. Didn't even think of that!