The GitHub autogenerated one is among the lamest I've seen.

Maybe something like the poster combo?

@dtolnay: wow, that's hillarious.
@oli-obk: I like the direction! I wonder what we could to do make it not look like the Pink Floyd poster. I thought about gravitational lensing but that's probably too far out there. Something from this app might work.
Another option might be some play on aqua regia, based off of Bohr dissolving some gold Nobel Prizes to hide them from Nazis, and then reconstituted them after the war.
that's a pretty cool app

I made an icon, just a sketch right now, but the idea is there. What do you guys think?
@Paluth That's not how sprockets work! :)
EDIT: Oh wait those actually are gears... to which I say heresy. :P
we can churn the gears a little with each major release! :)

Was trying to do a dissolving effect, but couldn't get it to look right 🙁 oh well!
What about a picture of the rust gear printed on a piece of paper?

Started off trying to turn the rust gear into a sun... kinda ended up with a yin/yang thing at some point... eh :/
I appreciate that the cogwheel is a recognizable element of Rust's logo, but I find it to be a rather hackneyed symbol in OSS. It would be nice to try something different, e.g. a cheap geometric bauble:

@tapeinosyne I agree with you and I love your design. Would you or anyone else be willing to put some more time into this? I think we can make something work.
Things I like:
Things that would really sell it:
I'd be happy to hear from others in this thread and refine the design. A benefit of these baubles is that they can be crammed through cookie-cutter steps to extrude variations; it's easy to iterate on them.
So, here are the basic elements of this particular bauble:
It only takes a few minutes to sketch an alternative design based on these steps. I used Input Serif Compressed in medium weight, a palette based on the Solarized color scheme, and a simple pattern of pips. Now, tasked with adapting the bauble to a different form factor, I can renounce any sophistication and nevertheless obtain tolerable results:

It is similarly easy to experiment with different patterns:

Less so with minimization, which can seldom be achieved without some tedious pixel-wrangling. (At least, not with Affinity Designer; it could be that Illustrator offers better rasterization.)

If we were to identify a variation we liked well enough, it wouldn't take long to finalize a design (ensure alignment, adjust spacing, and so on). Meanwhile, we can experiment without much effort.
Most helpful comment
@dtolnay: wow, that's hillarious.
@oli-obk: I like the direction! I wonder what we could to do make it not look like the Pink Floyd poster. I thought about gravitational lensing but that's probably too far out there. Something from this app might work.
Another option might be some play on aqua regia, based off of Bohr dissolving some gold Nobel Prizes to hide them from Nazis, and then reconstituted them after the war.