Rails performance analyzers
What are the preffered plugins for monitoring and analyzing the performance of a Rails app? I'm looking for both database/query analyzers and the rest of the stack if possible, though not necessarily all in one plugin. Which ones do you recommend?
( Bonus points for free ones :)

For example, [this one][1] looks spify.


  [1]: http://railstips.org/2008/9/17/rails-app-monitoring
Rails performance analyzers
===

What are the preffered plugins for monitoring and analyzing the performance of a Rails app? I'm looking for both database/query analyzers and the rest of the stack if possible, though not necessarily all in one plugin. Which ones do you recommend?
( Bonus points for free ones :)

For example, [this one][1] looks spify.


  [1]: http://railstips.org/2008/9/17/rails-app-monitoring