To try out some of the public apps for Excel or build one yourself. Note that it is absolutely addicting when you see it all working together and a lot of fun. Finally I can break out the box and truly go nuts with any data visualization I want without excessive barriers and pain!
If you want to build one for yourself, this is where I started: http://msdn.microsoft.com/en-us/library/jj220082(v=office.15).aspx and http://msdn.microsoft.com/en-us/library/jj220065(v=office.15).aspx. You will need a free O365 Developer account that you can get here: http://msdn.microsoft.com/en-us/library/fp161507(v=office.15).aspx and Office 2013 Public Preview.