I like wolves, but just "wolf" as an username would be lame (okay, "Terrawolf" isn't that much better). I thought about "Firewolf" as an username, but I didn't really like it, so I tried the same with Erd- (earth), wild-, Regen- (rain) and Icewolf, also with Pyro-, Aero- and Aquawolf and after that I came up with the name "terrawolf". I liked it, and now I use this name already for about four years.