Restaurant-goers with time on their hands and a penchant for witty, concise commentary can sign up here to register their opinions for the 2007 Washington, D.C./Baltimore Zagat guide. Provided that ratings are submitted by March 12, participants will also receive their own copies, in which their wry assessments may be immortalized in print. Though DCist relies on DonRockwell.com for most of our food and dining banter, we still like Zagat because it’s concise and old-school…