Some folks are missing the OP's point: trade scripts are useful for much more than just "trading traffic"
A good trade script will let you easily redirect "undesirable" traffic in real time (better / easier than .htaccess etc.), and often provide a more "readable" snapshot of your network's internal traffic.
It's also a great way to build toplists as a way of equitably distributing your back links.
Click counting is another major benefit, and while GA, piwik and other stats packages can show you this information, a decent trade script can put it into context that is useful.
I never used trade scripts to "skim" traffic or for other "typical" uses, but the gateway they can provide is an awesome tool for adult webmasters. It's been a while since I looked at what's new / hot in trade scripts and what they can do today, but they help build (better quality) traffic -- even if you don't link to anyone else.
