Since Napster was introduced in 2000, there has been a succession of file-swapping software programs. First it was Napster, heralded as the third most popular search term of 2001. The government took Napster down, leading to the rise of Morpheus, the fifth highest-ranking search term of 2002. When Morpheus had difficulties, it was replaced by KaZaA. KaZaA was the number one most popular search term of 2003, but fell to number 12 overall in 2005. For the first time since its debut more than a year ago, LimeWire (#13) lands higher than KaZaA on this week’s Lycos 50.