Aha. Livejournal is using the same trick as Squidoo for generating passive income from outbound links.
1. A third party company gets affiliate companies to sign up with it as an advertiser (Outboundlinks).
2. LJ passes all clicks to links through Outboundlinks.
3. If the link points to a company that's paying Outboundlinks for advertising, then LJ gets a piece of the pie.
Frankly, I'm less offended by this trick than some people, because the days of the free internet (when it was illegal to make money on the internet -- it was, once upon a time!) are gone. People don't just make websites to benefit the world. They build them to make money. Ergo, I'm not surprised when LJ pulls another of these tricks. It's not here just to let us share fanfic and vent.
Buuut, it's another invasion of privacy, and they haven't told anyone they're doing it.
ALSO, it doesn't quite work right. (A) it mangles any affiliate links YOU have added to your LJ, if you happen to be someone making a few pennies through affiliate marketing (I don't, but I've seen a few who do), and more importantly, (B) the script mangles links to some websites. E.G: crittersbythebay.com gets redirected to ebay.com. THIS is a problem.
THEREFORE:Here is how to disable Outbound Link Snooping on your Livejournal