Consider checking out US Dept of Commerce's Census of Governments - it has a lot of information. There's also a big trend of state/local governments opening their budgets and expenditures to the public in new and engaging ways. Some examples:

- http://www.checkbooknyc.com/

- http://budget.dallasopendata.com/#!/year/default

- http://miamidade.budget.finance.socrata.com/#!/year/default

- http://budget.topeka.org/#!/year/default

* Disclaimer: I work for Socrata which powers all of the above links except for NYC Checkbook