Jan 20 2009: created

There is a good collection of simple CMS and wiki gems available for Ruby webapps, most prominently the Ruby on Rails framework. In addition, there are several interface and integration frameworks either based on Rails or presented as alternatives to Rails which provide a solid foundation customized Ruby web applications.

Updated Sept 19 2008: added Ruby/EventMachine links
Updated Sept 19 2008: more links for Ruleby

Not a major category among the many rule engines implemented in Java and other languages. In this case, I've pushed the definition of 'engine' to the limits so I can include some of the more solid and interesting implementations.

Jan 31 2009: ruby-lang.org has released the first production version of Ruby 1.9, some bugs and problems with gems, also see Ruby 1.9.1 Released - Fastest Ruby Ever.
Updated Dec 14 2008: link for Ruby Shootout.

Some useful links.