Budget calculator shows major expenditures and income of the government and their relationships, it also allows you to "play" with government figures (lower or increase taxes, hire more teachers, decrease police wages, call for foreign aid...), and it will also calculate your contribution to the state budget on each count of taxes as well as how much of your tax money is spent on any of the expenditures (health care, pensions, education, social, agricultural aid...).

Zindex is a research project rating the transparency of public tender processes of public bodies in the Czech Republic.

Atkläts makes Latvian government spending transparant. It offers government an easy to use platform to publish data, and provides citizens insight.

A visualization of Italian government spending per region, and policy area for 2002-2008.

ComoGastan (How is it spend?) provides insight in how public tenders are allocated, as well as subsidies. Recipients and amounts are listed. The public can indicate if they think a project was necessary, the money seems reasonable, and if the decision seems to be objective.

A beautiful visualization of how the UK budget is spend on different policy areas. Also possible to look at info per nation in the UK and regional. Also contains historic info and time lines.