List of known worlds(in the order they were added) with rabbit holes:

Computer Plaza (9)
Donnybrook Beach (0) Check
Handy's Tools (1)
Imladris (3)
Dragons' Teeth (0) Check
oopsee Creations (0) Check
MT Design - the Kitely Shoppin (5)
MT Sexy Secrets (0) Check
Sierra Avatar WORKSHOP (2) Check
Regio Excelsior 2 (-1) Check
Skysong (0) Check
The Galleria (-1) Check
Oakes Valley (1)
Midtown Arts Museum (1) Check
Consortium Park (1)
Unofficial 3D ADA Toolkit for Lo (-1) Check
City Life (6)
French Quarter ()
Panthalassa (0) Check
Play-Work-Learn (2)
Egypt (1)
Hosoi Mura - Edo Honshu Japan (0) Check
Touchstone (0) Check
Mental Design (0) Check
Picture Book (2)
April Hunt LAUNCH POINT (0)
Marcat (4)
CheriNet Virtual HQ (-1) Check
Cherry Network Centre (4)
CHARE Village (-1) Check
Paradise Delight II (-1) Check
Sierra Jakob Designs Headquarter (-1) Check
GothixGrafx Crematorium (3) Check
Dust (7)
Poesy (0) Check
Freda's Retreat (0) Check
The Township of Llanfarian (0) Check