I am a big, big fan of tools that monitor the Web. Some of my favorites include Google Alerts which I use to track where our stories show up, AreMySitesUp, which I use to keep an eye on Web site uptime, and PriceProtectr which watches for drops and increases from various retailers. Trackle, a service that's coming out of private beta on Tuesday, is hoping to replace all three--and many others--by corralling all of these various alerts into one, large in-box. Is it a keeper? I think so.