The places I know include:
Any other suggestions?
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best source for global data imho is naturalearth:
I collected a big list of public available data here:
http://desktopmapping.blogspot.co.at/2012/06/diverse-vektordaten.html (its in german, but you can just follow the links e.g. in the section global))
The answer really depends on the area, and type of data you are interested in. One of the best locations to get POI and road data is from OSM. Cloudmade provides this data in an easy to use manner.
Update As Uffe has mentioned in a comment, the Cloudmade data is quite old. You can download the data from Geofabrik here