I posted this on Linkedin a while ago, but obviously things get pushed down in the group history until they are forgotten.
This is quite a clever Crystal Report (if I do say so myself) which displays when selected Services were impacted over a set time frame in quite a nice graphical way:
(Obviously I deleted the service names on the left, but they will be replaced by your service names when the report is refreshed.)
If you want this report (free!), drop me an email at firstname.lastname@example.org.
For more cool information about ServiceNow Reporting, please look here!