So I made a D20 table, you can roll once for a quick generation or three times for extra randomness. Some of the ideas are taken from actual coins (horned turtle for example). I'm sure you could use this to add backstory to a dungeon, giving some explanation of it's origin or just as some throwaway flavour.
|Coin Design Generator||http://brushoffumbling.blogspot.co.uk/|
|D20||Side 1||Side 2||Shape|
|1||Tentacle monster||Head of a crone wearing a crown, 50% side view, 50% front view||Round|
|2||Dragons Head||Head of a child wearing an elaborate hat, 50% side view, 50% front view||Square|
|3||6-legged Horse||Head of a screaming man, 50% side view, 50% front view||Triangular|
|4||Burning snake||Head of a donkey, wearing a crown, side view||Rectangle|
|5||Wasp||A broom, “wearing” a crown||Star|
|6||Lion||Bearded man wearing an earring||Hexagonal|
|7||Flying Crocodile||An orange being launched from a sling||Hexagonal|
|8||Owl||Bare-breasted barbarian queen||Square|
|9||Horned turtle||Humanoid skull||Rectangle|
|10||Pegasus||A hand holding a torch||Round|
|12||Wheatsheaf||A beer glass||Pentagon|
|13||A fairytale castle||A beast-man with a disturbingly large phallus||Round|
|14||Tree||A white cat. You're not sure how you know the cat is white, it's just a feeling you get||Round|
|15||Eagle||A NASA space shuttle||Round|
|16||5 pointed star||Coloured pattern of dots that gives you a headache if looked at too long||Star|
|17||Triangle||A horrific symbol you can only look at from the corner of your eye||Square|
|18||Ancient script||Some sort of unidentifiable mechanical device||Triangular|
|19||Spiral||Alien skull with 3 eyesockets||Pentagon|
|20||Alien Writing||Complex geometric design||Hole in the centre, roll again for shape and shape of hole|
Feel free to add to it or whatever, the table can't be big enough. I'm sure I'll be adding extra stuff to it eventually, a D100 would be ideal.
Stupid blogger, I can't seem to get the screen dump to be readable without it going into the border, sorry it's so ugly.
Edit: The screendump has disappeared, so I've just copied in the table, hopefully it's easier to read now. Seriously, why the fuck can't blogger deal with tables?