I recently discovered a nice app for iPhone/iPad which is capable of tracking visits.
I thought it can't be better than Google Analytics but after all I tried since it's free and... surprise... this thing does not require to put any code on website... just embed the generated image and that's it.
So I started to use it with my auctions and forum posts... It works

So I am not the owner of the site and still I can track who loads the page ;]
I receive a push notification instanly when anybody enters every tracked site which is another cool feature.

I must say I couldn't come up with such idea with hiding tracking mechanism in simple gif file

Since it's free I recommend trying the app: