There is a place in the desert where, it is said, sphinxes come at sunset. There, one may hear their music, played on harps. It is said that this music mimics the music of the spheres, which only sphinxes can hear.
I got another interesting answer to my quora.com question, here.
I recently asked a similar question on quora.com. Most of the answers weren’t very interesting to me, but one was. It’s here.
Still working on the Underworld. I’ve added cave-ins, jammed doors, and doors that ask you riddles. Next up, secret doors.
I just finished another section of My Name Is John Carter, so I should have more time to work on this for a while [edit: and just after I wrote that, I got a big editing job].
This twitter account apparently posts a randomly-generated fantasy map every hour (click the picture to go there).
There’s an article here about how they’re made.