I came across Wakoopa few months ago, but never got round to using it. Well today I installed it on both my desktop and my Tablet PC.
It's an application which shares the applications you use either publicly or with a list of friends by posting the applications, and how much you use them onto their website.
You can see what I'm using here.
The application installed on the system is very lightweight. Over the last ten minutes its used on average less than 0.01% of the CPU, and its working set is just under 3MB. It sits in the tray, but the icon is relatively attractive. Although I have told Windows to always hide it. The only thing I can really fault with the application itself is the installer wasn't digitally signed.
If you're using an application you don't want people to see can also tell it to pause tracking.
It's certainly interesting to see what else is popular, I figure seeing what games people are playing will be quite interesting. World of WarCraft is leading the pack by a wide margin. It's also good at seeing how much junkware is on people's computers, I don't even want to imagine how poorly some of these people's computers must run.
Worth checking out if you don't mind people see what applications you're using.