DC's Office of the Chief Technology Officer maintains what might be the biggest municipal data catalog out there:

http://data.octo.dc.gov

The World Bank's is probably the most well organized/designed:

htt://data.worldbank.org

The Civic Commons wiki catalogs these from a few different lenses: data catalogs, initiatives, policies, guidelines, etc - http://wiki.civiccommons.com/

It also links to many other resources that catalog these - http://wiki.civiccommons.com/#Other_Open_Government_Data_Resources

About a year ago the city of San Francisco passed an open data law and established http://www.datasf.org/ (Beta). Since then 200 sets of data have been released, and at least 50 apps have been built (by non-government people)  using the city's data. EcoFinder helps people find recycling locations for all kinds of items; SpotCrime plots crime incidents and sends alerts to residents; and Routesy lets people plan trips on public transportation and provides real-time information about when the next bus or train is coming. For anyone who relies on public transportation, this would be hugely helpful. It's apparently the first *law* of its kind -- at least at the city government level -- and could perhaps serve as a model for other city governments to follow.

Read the text of the law at: http://govfresh.com/2009/12/san-franciscos-open-data-directive/. And here's a recent article about it (one of many): http://www.fastcompany.com/1701410/san-francisco-passes-first-open-data-law.

New Zealand representative at the IOGDC gave a success story on open licensing:
"Ocean Survey 20/20 Portal"- helped the government and non-government organizations better manage marine resources and and assessing environmental affects