High above Grendel's Children, the store for fabulous avatars, is a board-riding wonderland (ably depicted in this machinima by Pyewacket Bellman), the invention of Constantine Riel, which he dubs Grungeboardin'. You can ride for free, just be sure to follow the equipping instructions in the lobby. Getting there is a challenge, as it's three thousand meters up, so you need to use this teleport SLurl, just provided to me by Grendel owner Flea Bussy. (Tell me if you have trouble ascending.) Direct SLurl to Grungeboardin' at this link.