CDN usually =
Content Delivery Network. So fbcdn = Facebook content delivery network.
If the site you're on (and trust) also has a cdn script, it's probably OK. goodsite.com, goodsitecdn.com probably deserve equal trust levels. Subtract cdn from anything else to get an idea of who it is, as in Facebook.
Quantserve: see
http://en.wikipedia.org/wiki/Quantcast.
"Some of this information includes, for example, whether the Web page viewer is a male or female, whether the average viewer makes $30,000 USD annually or $100,000 USD annually, the age group of the viewer ... the Quantcast code causes the user's browser to access Quantcast's servers, at which time they can log the user's IP address and information Quantcast places in cookies that are stored in the user's browser. The cookies significantly aid in making inferences. Quantcast also provides affinities revealing other popular sites that the average viewer browses. This is possible by tracking "referrer" information that is normally included as part of every HTTP request made by the user's browser... In July 2010 BBC News reported that a legal challenge has been launched in the US against a number of websites amid claims that they were engaged in "covert surveillance" of users through the use of a Quantcast Flash application to restore deleted cookies."
Defeat this by proper cookie management, using the
RequestPolicy add-on,
RefControl add-on, and of course, blacklisting/untrusting quantserve.com.
There are a number of other such that I could tell you to blanket-blacklist, but they escape me at the moment. Not very many 3rd-party scripts, other than from
Akamai FAQ, are necessary or desirable. By all means use the feature
therube pointed to, but there are a number that can be blacklisted on sight. If I come across them, will try to add here. Anyone else, feel free.
Also, consider using
HOSTS file to block about 20,000 undesirable sites, scripts and all.
Edit: By default, NoScript runs a
surrogate script for Quantserve (and some others), but I prefer to block them outright, to save the bandwidth and loading/response time.
Edit 2: Type
about:config in the address bar, and in the Filter Bar, type surr
This will bring up a large list of default surrogate scripts, from many of which you can extract sites to blacklist. It reminded me of yieldmanager, revsci, and many others.
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.20) Gecko/20081217 Firefox/3.6.15