The service at tiddlyspace.com has now ceased operation. It was created in 2010 by the Osmosoft team at BT, and generously operated for the community by them and their successors until December 9th 2016.
From http://tiddlyspace.github.io
This repository contains the DNS zonefile for tiddlyspace.com. It redirects the front page of TiddlySpace to the holding page. Owners of spaces may send a pull request to redirect the URIs for their own spaces to wherever they wish.