Well I didn't realise, or maybe I just plain forgot, that these reports and the necessary support infrastrucuture come with Reporting Services under the extras folder on the CD - all useful stuff for report heads.

Longest Running Reports
Most Executed Reports
Report Exections By Hour
Report Parameters
ReportsByMonth
ReportsByUser
ReportsExecutedByDay
ReportSize
ReportSuccessRate
Todays Reports

For more info see http://msdn.microsoft.com/library/default.asp?url=/library/en-us/rsadmin/htm/arp_rslogfiles_v1_88gy.asp?frame=true