Alerts based on the 95th Percentile

Hello, I was wondering if anyone has been able to or has tried to create alerts base don the 95th percentile? What I am referring to here is that 95th percentile line we get when looking at a hard disk, CPU, RAM etc.... I was wondering if it is possible to create an alert that triggers when the 95th percentile (or 96th , 97th..) has been reached? It owuld be nice to have that as an alert to see which nodes or interfaces, volumes etc are outisde their normal boundaries of operation. Jens