Got a favorite gem you want to tell the world about? Or one you want to warn other people about? You can do both with Gemtacular!
Gemtacular (http://www.gemtacular.com) is a place to rate and review Ruby gems. It’s a great place to not only find opinions on various gems, but also to see the most recent gem uploads, find the most highly rated gems, or just search for existing gems.
Some quick guidelines:
* Gemtacular is not a place to report bugs. Use the project page for that.
* Be nice. If you have a problem with a particular gem, please explain why without getting nasty.
* Don’t be lame and rate your own gems.1
1I already have a feature request in to try and prevent this at http://rubyforge.org/tracker/index.php?func=detail&aid=10063&group_id=2863&atid=11067

Very nice service! Does exist something similar for Rails plugins too?
Tragically, they didn't claim gemiocre.com and gemiotic.com. So much for unbiased ratings... ;)
For rails plugins you have Agile Web Development
did a big article on this on my blog a while back, with my favourite gems,
link...
http://www.red91.com/articles/2007/05/29/gems-commands