I recently realized that even though I was monitoring my Squid “system” very well, I wasnt monitoring Squid well. I had little knowledge about cache-hit ratios, how much WAN traffic I was saving, how much I was speeding up (or slowing down) end-users.
I quick googling and I found http://tanso.net/zenoss/squid/. This link explains how to enable SNMP monitoring of Squid, and then includes a ZenPack to monitoring right in Zenoss. I installed this and set it up, and within a few minutes I was beginning to recieve information.