Google Gadget “creator page” and lists datatype
Feedsparks uses the new (as of Jan 17th) “list” datatype which google added to their gadget API. It enables a simple but nicely designed interface for configuring a gadget like this one. But the UI for the new datatype has confirmed problems outside of adding the gadget to your google homepage (which works flawlessly). Hopefully google will fix this shortly. Until then, the prior post describes a workaround you can use.
You can read some background (the dialog with google) at the google group for gadgets.