This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
What is one hidden or interesting feature in Grails that isn't apparent on first use or first application that you develop with it?
For me, one of the neatest features I discovered after playing with Grails for a bit was the Spring DSL that lets you create/manage Spring beans with Groovy code, not just xml.
In your opinion, what one feature makes you go "This is so cool!"? I know there are many with Grails.