I am writing five blog posts about the goodies that have appeared in Edge Rails over the last few months. Two columns were posted at the end of last week. Three more will appear next week. You may have read about some or all of the things in the posts, but perhaps the examples will be novel. I am also happy to take suggestions from other Railers -- send me email this weekend so I can include the material in the remaining three posts.
You can also find a great, in-depth comparison of Groovy on Grails, JRuby on Rails, and Helma on that same page. The comparison was written by UCSC computer science grad student Tom Austin.