It is true that it is difficult to find Open Source projects that provide a real Squid Web administration interface
Here it is a real Open Source project that should provide this topic.
Artica For Squid is a user-friendly Web ajax administration console that try to provide all necessaries needs in a company.
Also there are several other features…
First You need a Free system:
For examlpe Fedora, Ubuntu, Debian, Mandriva, CentOS
You can also download the ISO (both 32/64 bits) on SourceForge
To obtain more informations and for support needs, there is a dedicated Forum: