Since I have never gone by my birth-name online (and almost certainly never will), over the years I've been known by various names in the collaborative writing communities and associated places where I've hung out. Many of those names were specific to a particular time and place and although I'll still answer to them (because nostalgia is my middle name) I grew out of them, or grew out of the person I was when I wore them.
Viridian Green was a name I chose for myself some 4 or 5 years ago as a baggage-free alternative to the pseudonymn I was best known by at the communities I was frequenting at that time - a tight and rather incestuous world whose appeal was starting to sour for me. I've switched to using it a lot more over the last year since it's become a name I feel comfortable with, a cross between a Craft name and a nom de plume/guerre.
At the time I first adopted Viridian Green as my pseudonym, I wasn't aware it was also the name of a design movement based on a bright green environmentalism philosophy*. Without even knowing they existed, I'd even unwittingly chosen the name for the same reason the Viridian movement chose it. Green is suggestive of nature and environmentalism, and yet viridian looks cold and not entirely natural. It's the colour of futurism and technology as much as it is of nature. It's the colour of sea serpents and cats' eyes, it's deep water beneath overhanging leaves along a river bank and C-beams glittering in the dark near the Tannhauser Gate.
The Viridian Design Movement closed in 2008, but I am still here embracing my own personal manifesto.
* "We're Viridian Greens, the Viridian movement. That's because we're green, but there's something electrical and unnatural about our tinge of green. We're an art movement that looks like a mailing list, an ad campaign, a design team, an oppo research organization, a laboratory, and, perhaps most of all, we resemble a small feudal theocracy ruled with an iron hand by a Pope-Emperor." [http://www.viridiandesign.org/]