Netvibes has developed an Universal Widget API which can be used to create widgets that work on multiple platforms. Currently a widget using their API will work on Google IG or the Netvibes mashup site. You can find the documentation and forums on the UWA at http://dev.netvibes.com/doc/.
I have created a few widgets but they don’t work on Google IG or Netvibes. They usually only work when I open them in my browser as a file on my system. This has been very frustrating for me. The problem is their sandbox which does not allow you to get XML from a third party web site. You are supposed to use a PHP script as a proxy to work around this problem. However, this does not always work for some reason. Another problem I have is that my web hosting company is adding a script at the bottom of my web pages for the site statistics. This script is preventing my Netvibes widgets from being well-formed HTML so they won’t work on Google IG or Netvibes.
I do have an example widget for Stickam that you can view but you will be unable to use it on Google IG or Netvibes.
I was also thinking about developing some Pageflake widgets but I really need a development web site where I can host my projects.