Google allowing developers accessing data using RSS - http://code.google.com/apis/gdata/basics.html

Few of them:
http://code.google.com/apis/documents/overview.html
http://code.google.com/apis/spreadsheets/overview.html
http://code.google.com/apis/youtube/overview.html
http://code.google.com/apis/opensocial/

Market Data - http://rodrickbrown.com/blog/?p= http://finance.google.com/finance/historical?q=NYSE:LEH&histperiod=daily&start=25&num=25 http://finance.google.com/finance/historical?q=HKG:0005&histperiod=daily&start=25&num=25