ad tracking/something you might have fun with
If you'd like to get an idea of how many websites track you for advertising purposes, etc, using google analytics as an example, you can do this...
What you do is redirect all 'analytics' code to your own webserver (so you can look at the log files), and then in the course of your daily search you will see which websites track what... To do this:
a) You will use notepad to edit your 'hosts' file, which controls which websites you have access to. So start menu->programs->accessories->notepad. For windows Vista/7 users, you may have to run notepad with admin access.
b) You then open the c:\windows\system32\drivers\etc\hosts file
c) Add the following lines, replacing "127.0.0.1" with whatever webserver you are running (you'll just need to get your web server ip address using any online tool)
127.0.0.1 domains.googlesyndication.com 127.0.0.1 pagead2.googlesyndication.com 127.0.0.1 adservices.google.com 127.0.0.1 video-stats.video.google.com 127.0.0.1 ssl.google-analytics.com 127.0.0.1 www.google-analytics.com 127.0.0.1 4.afs.googleadservices.com 127.0.0.1 feedads.googleadservices.com 127.0.0.1 imageads.googleadservices.com 127.0.0.1 pagead2.googleadservices.com 127.0.0.1 partner.googleadservices.com 127.0.0.1 www.googleadservices.com 127.0.0.1 www.appliedsemantics.com 127.0.0.1 service.urchin.com
e) To change it back, simply remove the lines you added, and regular ads will show up again.
Although I just posted this as a google example, you can use it for testing/tracking other purposes, as well as with your own sites (if you want to make sure everything is working a-ok).
Enjoy!