I had an idea that would be pretty handy when handing out Tableau Desktop workbooks, but I don't know if Tableau has the infrastructure/functionality to support it right now.
I wanted to have a button on my dashboard which would allow the viewer (using Tableau Reader) to dynamically turn on/off annotations. The idea would be that the annotations give information about the dashboard, as well as information on what buttons to click and stuff like that (basically permanent tooltips or markup).
After the user figures out their way around the dashboard, they could turn off annotations. This way, I could save whitespace that would otherwise be used in captions and helper text.
Note: I opened up a forum question about this here: http://community.tableausoftware.com/thread/125397