This 'beta' icon for codegolf.SE is pretty lame.
So, in order to create a framework for my own proposal (I dare you to do better!), I ask "What's a good icon for Programming Puzzles and Code-Golf?"
Stealing Keith's idea, here's a "code-grinder" constructed by reversing the Meta-Stack Overflow icon, adding some space for a "grinding chamber", an output chute, and some smaller things coming out.
Instead of an icon which represents puzzles, why not an icon which is a puzzle? Maybe something encoded in the 256 possible pixels of the 16x16 icon?
EDIT: Thinking about it further, 256 bits could hold 32 ASCII characters, which might be enough to hold a J or Golfscript program...
EDIT2: :-) The ridiculousness continues...
Maybe convert the following to an icon?
0100111101100011 0011011011011100 1001110000110111 0110011001000011 1101011110000010 0001101000111101 1011110111111011 1101101110011011 1010001000010101 1000100001100010 0111000011001011 1001101001000111 0000110110111001 1101000100100111 1111011010100011 1110101001010000
With apologies to Gnibbler for appropriating his code.
The icon would look like this:
Picking up Gareth's suggestion, why not make the icon a tiny bit of Piet code? Codel size could be 2 to be a bit easier to distinguish from noise, albeit with the problem that less code can be written.
But I think esoteric programming languages exemplify the recreational part of what we're doing here quite well, regardless of whether they are good for golfing or solving puzzles (Piet is definitely under-represented here).
"Puzzle" is a lot easier to convey in a small icon while still having space for some code than "golf".
I'm probably awful designer, but I decided to try using U+26F3 as an icon.
In 16x16, it looks way nicer.
I was thinking of some sort of code grinder. I'm not sure you could make it very small and still be legible, though.
John Tenniel's Illustration for Alice in Wonderland portraying Alice attempting to play Croquet with a flamingo and two hedgehogs.
Perhaps with "x=x+1" on the hedgehog running away and "++x" on the one underfoot.