It was actually a Shadowrun character name originally - I created a shaman that was of the Pegasus totem, and had an affinity for storm-type things (his main attack spell was lightning bolt, he had an affinity for Storm Spirits, etc...) so in the process of trying to create a "Street Name" that summed him up, I ended up with Stormfeather.
Fast-forward verrrry slightly to me trying to register new usernames with new places on the internets, and less and less can I find a place where the more common names I used to go by (like "Trickster") were taken. And I've always really hated going by, say, Trickster817 or something lame like that. I really liked the Stormfeather character, and I liked the name as well, and when I started trying it out various places I found it was almost *never* taken at the time, so... there we go.
(Nowadays, it's still not taken in generally smaller areas of the net, although on places like a WoW server or something, chances are even that's snatched up. But hey.)