Oracle's (free, comes with the database) utilities UTLBSTAT/UTLESTAT will produce you a report with a section on wait events statistics. In 8.1.6 those two utilities have been much improved in a utility called STATSPACK. I haven't played with it yet, however there were some in-depth articles about STATSPACK in some later isues of Oracle Magazine, and my impresion after reading those articles was that Statspack is a couple of magnitutes more powerfull than utlB/Estat

HTH,