alternatives

Boost provides free peer-reviewed portable C++ source libraries. We emphasize libraries that work

CLI (part of the Jarakta project)
http://jakarta.apache.org/commons/cli/index.html

This is Java library. 
The interface seems to be similiar, except for data storage.
1. Instead of variables_map, the library can store the data
as Java system properties.
2. The class Option, which uses to describe the data, is also
   used to keep the value. In contract, I keep them in separate
   place. This facilitate using the same options description
   for different data sources.

TODO: Need to check that Option.setType method does.

Werken.opt
http://sourceforge.net/projects/werken-opt/

This is a much simpler library then CLI, which
somewhat less features.

JArgs
http://jargs.sourceforge.net/

Another Java library. Has a fixed set of value types it can
handle.

Options (by Brad Appleton)
http://www.enteract.com/~bradapp/ftp/src/libs/C++/Options.html

This is very lean library. It does not provide argument validation,
and the only iterface is iteration over arguments. An interesting
iterface decision is using chars to identify presense of option's parameters.
This may be moved to my library (|, :, ?, *, +)

Cmdline (by Brad Appleton)
http://www.enteract.com/~bradapp/ftp/src/libs/C++/CmdLine.html

This library provides options validation and storage. Unfortunately
1. Only a fixed set of data types is supported.
2. It's intrusive -- one has to declare variable of "class ArgChar" or
something, and then extract data from there.