Apache Performance Monitoring
 

Does anyone have any recommendations as to some Apache performance monitoring software?
I use Webmin on my websites and use Google Analytics but I find I want something graphical that has more real time and immediate past performance metrics available.
So for example my users tell me of a performance issue a few hours ago today and I have no real way of spotting this without wading through log files. So what tools can help me to see what is going on in a graphical way with my servers?