There is a meme going around where you ask people about some of their userpics and then they post about what they mean.
Well, too bad for y'all, because you don't get to ASK, I'm just going to TELL you.
This is the first userpic I uploaded. It's labelled "Froude number", because that's what Leper & I were saying when it was taken. Along with a large pile of other folks, we went to the scale model of the San Francisco Bay in Sausalito, and they had a sign talking about the Froude number, a dimensionless similarity number for objects moving through water. We took a picture because it's funny. Frooooooude. I use this icon for talking about science, or more often just for generally pontificating.
This is my "Mister Cranky-Pants" icon. I'm sure its uses are obvious. Mostly I'm just posting it because I know there are a number of you who are delighted by it, so I try to use it whenever it's warranted.
Chibi Dr. Tectonic is for talking about games.
This is a picture I took in a darkened bus, without flash, riding back from the airport. I included it as a lark in a set of pictures I sent to Jeb (50poundnote) as raw material for a bingo card, and he went and turned it into art. I use it when I'm talking about art, dreams, ineffability, and the like. (The text is Japanese kanji for 'dream'.)
In college, I lived at a phraternity. This is the logo we came up with for representing our haus. It's the 'xiohazard' logo, because it's xi chapter of the national. I recently added it for talking about teply things. I think that the actual graphic is mostly eto_theipi's doing. (And perhaps the design is, too; I am ancient and drooling and can't remember anything any more.)
50poundnote) as raw material for a bingo card, and he went and turned it into art. I use it when I'm talking about art, dreams, ineffability, and the like. (The text is Japanese kanji for 'dream'.)