It's the Web server mirror.
It's the mail server mirror.
It does seti@home.
oh and Grish uses it for Web surfing, so that's 4 functions.
Just noticed from my BOINC stats that it hasn't been running seti for about 3 weeks. Just had to reinstall BOINC... and what a fiasco that turned out to be.
I don't like Macs.