How about this for a crazy use case: I have been testing a configuration that will allow me to use the Mini away from my house with no monitor, mouse or keyboard or even a real network.
I am running the Mini headless connected to my XP Laptop via a firewire cable and accessing it with VNC. Tuning VNC for the firewire bandwidth gives me performance that is nearly as good as connecting local. Moving large windows stutters slightly, but everything else is smooth even animations and video.
Some of the tricks:
Many people have trouble booting a mini without it being connected to a monitor. There are instructions on the tubes for soldering up some resistors to a DVI connector to fake the monitor. I found that I didn't need to do that if I just left my DVI to VGA converter attached. I'm using some off brand so mileage may vary.
You need some sort of network between the mini and the laptop of course, the faster the better. VNC is a pig with bandwidth. An easy trick is to just use a firewire cable between the two. Both sides will acquire an address. I found that if the Laptop is booted up first the host names will resolve. That's a good thing, else I'd have to set the mac up with a static IP.
Don't use Leopards internal desktop sharing. Install Vine Server, it is much faster and supports more encoding options. Setup Vine Server to run the system server as well as the desktop server. This will allow you to see the log in window at boot.
All VNC clients are not created equal. Normally I swear by UltraVNC. I have it optimized for use on WIFI G and slow Internet tunneled through Hamachi. In the case of high speed networks like firewire or Gig E, however, RealVNC is coming out on top. It beats UltraVNC and TightVNC using the same encoder settings - go figure. I set it to HexTile encoding with full color. It is blazing fast.
As a side effect of booting without a keyboard I am now able to use my 'windows' key as an 'option' key. This never worked for me through VNC before.