Trendrr makes graphing simple by including a drag-and-drop scratchpad that lets you edit and compare graphs with a minumum of effort. The system is based on the RESTful api, which means advanced users can hack together their own trends - there's an example on the site of graphing your computer's CPU usage over time. For everyone else, though, the list of built-in data sources includes popular sites like eBay and YouTube. Don't miss the gallery of popular graphs, which are sometimes informative and sometimes just funny.
