We all test our code. And coverage can be a helpful measurement. But are you sick of rcov failing with:
260 examples, 0 failures
/Library/Ruby/Gems/1.8/gems/rcov-0.8.1.2.0/lib/rcov.rb:699: [BUG] Bus Error
ruby 1.8.6 (2008-03-03) [universal-darwin9.0]
rake aborted!
This gem alternative seems to be good so far!
sudo gem uninstall rcov
sudo gem install spicycode-rcov --source=http://gems.github.com/

This is awesome, using it now for RightPact. No more Bus Errors !!!