you more arty they become, the less they're like the trem HUD, and so less right for the game. Anyone follow me here? :-?
I don't think I agree. This is supposed to be an icon for tremulous, not an ingame thing and if it looks arty, that might make the game look more professional. The icon kinda represents the theme of the game rather than the game itself.

By the way, if anyone wants the svg, just ask!
I'd love to have the svg for that. I think that, without the "T", would be awesome.
Edit: You guys need to stop designing at 128x128. (I know this sounds hypocritical coming from me) These icons will probably turn out fine when you scale down the svg, but designing at a size that won't be used (except in certain cases on OSX) isn't the best idea. The Tango Icon Theme Guidelines really have a lot of smart ideas about this kind of stuff, coming straight from professional icon designers.
http://www.durand.zephyrhosting.net/dump/tremicons/trem_icon_ah.svgI'm only designing in 128x128 because someone else started to design in that size and i guess i just wanted to keep the pattern. As it's SVG, it doesnt really matter anyway. On Linux and Mac, Im pretty sure the icons are usually SVGs and scalling won't be a problem. For those who use Windows, I've been checking that they look ok at the smaller sizes. Someone please remind me what the default icon size for windows is. 32x32 and 16x16, right?
Oh and I have been using the tango icons as a guide anyway, especially for the design techniques though I don't think tremulous and tango icons will go together well.
If anyone wants the icons in any other size, just say so.
I think durand's is a touch too busy and I don't like the T (a pure image logo I think would be nice) but it is pretty and nicely symbolic.
Try cutting the diameter of the outer blue ring so it has approximately the same area as the red on the left.
I was thinking of doing something similar to this one by a Turret.
Heres an Human vs Alien 1. 
Instead of doing that, I was thinking of making a cog a bit like this one but in 2D :

For the bicolor logo, make the T cutout.
Do you mean removing the T and having a cut through the rest of the icon? A boolean operation? Anyway, thats what I'm trying now with different fonts.