All of these pallettes correspond to a weapon from X4, X5 or X6 (none are original).
EDIT: As of 19th July 2011, I went with a new set of avatars: Grim Reaper Sigma from Mega Man X4, in various recolors (mostly same as above).
EDIT: Changed again, as of 31st March 2012. Also added four new ones (careful, scheming, assertive, priority)
EDIT: As of 16 September 2012:
EDIT: As of April 1st 2014: (with one new bonus one I made for posts about the 2014 FIFA World Cup)
Edit: I think I understand now: It's my avatar, isn't it? It makes me look angry.
Mine is Ark from Terrangima. Awesome game by the way.
I guess most of you know, mine is Squall from Final Fantasy 8. The image is from the ending sequence of the game.
and was made by applying various photoshop effects over the initial render:
Oh, yeah. I forgot. I was also fascinated with the concept of something glowing black. Also a noticable theme in these images.
Anyway, as time passed, thumbnails of became my avatar just about everywhere I used an avatar, and then when mood avatars were introduced here, there were some moods that none of these already-prepared ones were good for, so I went back to and applied even more photoshop filters, leading to the full spectrum currently visible
and 
Normally i would say Yes, but thennI thought "its not the same hack" so ill stick with meh.
<- My old avatar, for I've since replaced it.
My 
I shrunk the original graphics a bit, created a smooth gradient and added a blinking animation.
I have no idea why I chose it, other than being a fan of Mega Man NES games back when Mega Man 3 was new. The animation was just something I wanted to do.
Later on, when I introduced the concept of mood avatars on this forum, I took a new screenshot from Mega Man 4, this time unscaled, and created a custom program which dynamically changes the palette according to options given in PHP URL parameters.
. These appear in my posts today.
The different colors were chosen to intuitively reflect the moods present in the post's text. Color of the body, color of the shadow, color of the greebles and color of the ear-interior were all carefully chosen. However, color-to-feeling associations are largely culture dependent, so what is obvious to me is unfortunately much less obvious to others.
I have a few other avatars as well, but most are variations on this theme.
Some of the others are event-related, such as the Hanukah candelabrum.
In my profile appears the current default avatar (not used anywhere else), which is this:
[img_left]http://bisqwit.iki.fi/fliers/avatar/owner/glcav.png[/img_left]
It is a cropped section of my desktop background picture, which
also appears in the beginning of my most recent YouTube videos.
I just felt inspired to do it one day.
One day I came across Portrait Illustrator Creator, and I experimented with it and created a completely new set of avatars.
The new set was based on variations of this picture:
, such as: 
After negative feedback, I discontinued using that set though.
It did however resurface two years ago in an April Fools prank on tasvideos, whereupon I used Egypt-based avatars such as these two:
. A variation thereof appears currently on my YouTube account.
Arts and sprites of the Pokémon #162, the furret.
A furret fsjal an associate did for me.
Sprite rips and animations from the Japan only GBC pet ferret simulator Ferret Monogatari: Watashi No Okini Iri. This particular one is a silver mitt I have named Stuv. The only edits, aside from animation timing, were done to #13 to remove some sweat drops and #202 to color the eyes red.
Some photographs taken and shopped by Jeanne Carley.
A detail from this picture, drawn by one of the people responsible for the Peach Fuzz trilogy.
Hope that covers it...
