Farley never appeared in the other Animal Crossing games as of now. Many believe that he was replaced by Serena, who shares similar roles in City Folk. Both do appear in the fountain, and both give the player a better axe.
In the Prima Animal Crossing Guide, Farley is never mentioned, despite the clear label in the front: "All 236 animals revealed." What's stranger is a picture of Farley is shown in place of a snowman, yet no info on Farley is featured.
The statue in the Wishing Well is of Farley, which might be where he resides. Thus, there are theories that he talks to the player through the statue.
Along with Joan, Luna, and the player (In the Happy Home Showcase or in a Dream Town) Farley is the only character to have his own unique voice. His voice is very odd, and sounds like the more common male voice, but slowed down.