Might I recommend a map, even a blank one. People are going to go their own merry way with every race and not design them with intertwined histories unless you force them to acknowledge the fact that their race does not exist in isolation. If they have to pick a spot on a map and say 'THERE That's where my not at all furry race lives' then they are forced to contend with the fact that some other player's race is adjacent and must therefore write them into the history and culture of their own race. Doing this would make the world feel more real and organic and less the result of a random collection of ideas.