I don't know if youv'e read the reviews, but the main bottleneck of the MM is the 4200 rpm HD. If anything needs an upgrade it's that. There is a page I saw where some guys did the swap with a 7200 rpm notebook drive and got huge results (outperformed powerbooks). Just !!!
I'm sure the same guys do overclocking, they were mac gurus.
Carputer status: [-*---------]
Im thinking laptop...
Here's a thread with a lot of great info on overclocking the mini. Apparently they've located the 5th resistor and can potentially overclock it past 1.58GHz, although stability at and beyond 1.58 is still kind of sketchy.
I'll be vying for 1.58 after I get the 7200rpm hard drive installed.