Amir Salihefendic talks about Redis, scaling plurk.com and some python libraries on top of redis like bitmapist.
Amix talks about scaling plurk.com with redis. The slides are available on Scribd.
If you don't have the time to watch the video you should at least check out the mentioned python libraries:
The last one is really interesting if you want to do some custom analytics of your web site. There is also bitter, a php port of the analytics library.