For some people its very obvious, for others there might be some special meaning. If you feel so inclined, share the reason you have the particular screen name you do.
For me, Edcculus comes from being a ridiculously obsessed Phsh phan. There is a group of songs and narrative written by Trey Anastasio (the groups guitarist) called "Gamehendge" or "The Man Who Stepped Into Yesterday". You can read the story of Gamehendge if you like. In short, its a story of the pitfalls of greed.
Anyways, there is a character named Icculus, who is the god of the people. He lives on a mountain.
One day, I was thinking about it and it just hit me...Edcculus!