Once you create a gadget instance, you can share the URL you are at with others to simulate them being on this wave. You will actually be all working on the same gadget instance!
Note: This has only been tested successfully on Firefox 3 and Safari.
Here are those that have been tested with this emulator (link creates new gadget):
Built by Avital Oliver using CouchDB for storage. Inspired by Vidar Hokstad's two-iframe emulator. The code is on GitHub.