Normally, Second Life avatars cannot walk off the edge of a sim. But a simple trick will let you move your avatar off the edge. Even better, you can dance, walk, or fly!
I made a set of sculpts and a nice demo of this effect for an off-sim dance floor for Phaze Demesnes. I've put a bonus in, too: the pose balls have a modified camera control script that you can add to existing pose balls for special camera effects.
After you make this, you should end up with this 9-prim stairway to heaven:
More information including free sculpts and all the textures is at http://metaverse.mitsi.com/secondlife/posts/off-sim-pose-ball/