There are two applications on the JMP File Exchange that between them contain examples of probably all the functionality you'd need to do what you require:
(a) "Internet Traffic with Tree Maps" in the "Internet" section, which contains scripts for tree mapping and data filtering.
(b) "Google Finance JMP Script" in the "Finance" section, which pulls historical stock data off the internet from Google Finance based on a ticker and date range.
I'll guess you might need to incorporate an "update" button if the data you're downloading is changing rapidly, but that would be easy enough to do. You can get straight to the File Exchange from here: http://www.sas.com/apps/demosdownloads/jmpFileExchange_PROD__sysdep.jsp?packageID=000416&jmpflag=Y