The capabilities of Google Gadgets I described in a previous post on creating a personal portal are available for inclusion on your own web pages. To provide a demo, I must link you to a simple page external to this blog.
I encourage you to examine the collection of gadgets that are available. You may find a resource that those who visit your site will find useful and that you could not create yourself.
If you happen to be a Mac user and use Dashboard widgets, Mesadynamics offers a free resource for converting gadgets to widgets.