Bikewise is a crash, theft, and road hazard reporting tool put out by the Cascade Bicycle Club. It links a database of reported items with Google maps to allow pinpointing of trouble spots. The tool is very new so there's not a lot of data yet. Do you have any dangerous spots along your commute? Did you crash or have your bike stolen? Report them all here: http://www.bikewise.org.
Portland has a similar tool, called B-SMART (http://bikeportland.org/closecall/view_reports.php?). I haven't seen any recent news updates but it appears that people are still reporting crashes and hazards.
Anybody have any other online tools for cycling that they really like?