If you're like me and waiting endlessly for apple to release an apple cinema display with an iSight, then here's a cheap option.
Enter left: The Xbox 360 webcam
A little background information for you:
When I purchased my Mac Pro I was too much of a tightass/didn't want to wait too long for my Mac Pro to be delivered, so I went for the option without Airport/Bluetooth. However when I moved house, I was forced to switch to wireless to avoid a long blue cable running through my hallway (I rent so wall installation isn't an option).
After searching for endless 3rd party airport options for my Mac Pro I came across a dlink GWL-122 card which claimed to be mac supported. However after endless mornings of waking up to a kernel panic, I decided to bite the bullet and order an airport card for my Mac ($160 later...). Dick Smith Electronics were happy to accept the return of my dlink wireless stick but only in exchange for store credit.
The only thing I needed/wanted from dick smith was a webcam to skype with my family & friends, so I jumped online and searched around for a mac compatible webcam, aside from dodgy logitech mac compatibility reports I came across an thread on another forum claiming that the xbox 360 camera was 100% natively compatible with mac os x since 10.4.8, so I figured I'd give it a whirl.
After simply plugging the cam into a free usb port on my mac pro I opened photobooth and alas, webcam action!
Here is the photo taken with my cam through photobooth:
and from the otherside of the room with the iMac seen pictured above:
(less quality than the isight I guess, though I'm not an expert and could be due to lighting/focus aspects or whatever)
All effects are supported in photobooth and work great!
Along with iChat AV and Skype, I'm fully functional in the webcam area.
In conclusion, if you're like me and feel a bit jealous at iMac/Macbook/MBP users with their isights yet don't feel jealous enough to fork out $200+ for one on ebay/amazon/wherever for a firewire isight, then the xbox 360 cam at $60 makes for a great option for you Mac Mini/Pro users out there without having to play around with dodgy 3rd party drivers or macam.