Waves

http://www.infoq.com/news/2008/02/waves-ruby-framework

Why

• It is "next generation," an evolution of Rails.
• It's thread-safe and has a smaller footprint.
• It is much more focused on reuse, both within applications and across them: JITR, encapsulating applications within modules, and so on.
• The equivalent of routes are Request Lambdas, which are much more powerful and allow you to color outside the MVC lines when it makes sense.
• That is, code is automatically unloaded before it is reloaded, so that there are no artifacts left-over from the prior loads. The importance of this is that debugging is a bit easier, but also that you can hot patch production code reasonably safely using LiveConsole.

http://www.rubywaves.com/features