Here are some useful links for getting your hands wet with Groovy/Grails programming:

Programming Resources

Groovy resource: http://pleac.sourceforge.net/pleac_groovy/index.html

Plug-ins: Grails Plugins

Forum: http://grails.1312388.n4.nabble.com/

Blogs: http://groovyblogs.org/entries/recent

Book references: Recipes!

Design Ideas

Get the ideas flowing: 99designs.com

Quickly generate rounded corners: http://www.roundedcornr.com/