When a Web server (or Web site) is unable to handle the number of requests it is recieving and it goes down (generally due to the servercrashing), it is said to be "slashdotted." This expression originated from slashdot.org, a technology news and information site which became so popular that when it mentioned another Web site, that site would become virtually unreachable because too many people were trying to access it.
Now the expression extends to anytime a Web site experiences a surge in user traffic to the point of a grinding halt because it is mentioned on any other Web site. This often results in Webmasters having to pay huge bills if they pay by bandwidth. You may hear it like this, "I can't load the page, the site must be slashdotted."
Slashdot is so popular that traffic from its links can cripple small Web sites, sometimes for days. So a couple of fans have set up a site called Mirrordot to alleviate the problem by hosting copies of sites mentioned on Slashdot.