Code

Code for sketching:

• The MassDAL Code Bank. http://www.cs.rutgers.edu/~muthu/massdal-code-index.html.
• StreamLib: https://github.com/addthis/stream-lib. Check this: http://www.addthis.com/blog/2011/03/29/new-open-source-stream-summarizing-java-library/#.VTzMcJPl_VI 
• Hokusai: https://github.com/dgryski/hokusai. I have not used it, but the paper makes it look very ineresting. 
• Webgraph. Analysis of large graphs, contains the HyperANF and related code used for the Four-degrees-of-separation paper: http://webgraph.di.unimi.it/

Others I found. No guarantees of any kind, including they guarantee that they still exist.

• c++: https://github.com/hideo55/cpp-HyperLogLog/blob/master/src/hyperloglog.hpp
• Java: https://github.com/addthis/stream-lib/tree/master/src/main/java/com/clearspring/analytics/stream/cardinality
• Python: https://pypi.python.org/pypi/hyperloglog/0.0.8
• Ruby: https://rubygems.org/gems/hyperloglog
• Perl: http://search.cpan.org/~hideakio/Algorithm-HyperLogLog-0.20/lib/Algorithm/HyperLogLog.pm
• JavaScript: http://cnpmjs.org/package/hyperloglog
• node.js: https://www.npmjs.org/package/streamcount
• https://github.com/eclesh/hyperloglog/blob/master/hyperloglog.go