Findings:

• Popular Registries (superdoc)
• SS-N-12 Sandbox
• This is my universe. Go find your own sandbox.
• Reputation Graph Horizontal (superdoc)
• Reputation Graph (superdoc)
• The Sandbox
• The sandbox, it is full of shit (category)
• in10se's sandbox (superdoc)
• I One the Sandbox
• virtual sandbox
• Magical Writeup Reparenter (superdoc)
• sandbox

If you Log in you could create a "sand-box" node. If you don't already have an account, you can register here.