code snippets online

http://codesnippet.research.microsoft.com/

duplicate code detection

This seems like a stable project in working condition, it is worth a test. http://sourceforge.net/projects/pmd/

Another one that produces fancy graphs, but probably requires more reading of the documentation in order to actually understand what the output means http://www.ccfinder.net/ccfinderxos.html

Also interesting tool to try is the successor to Microsoft Labs PEX, Microsoft CodeDigger

Microsoft CHESS tool for concurrency testing