If you decide to play around with developing your own Google Gadgets, you may find these notes useful. They are gathered from the experiences of other developers using iGoogle sandbox for the first time.
Hints:
There are two Google gadget developer guides, one for the earlier 'legacy' version of the Google gadget API and one for the new version which supports OpenSocial. Make sure you use the new one.
Here is the guide for the iGoogle sandbox, a development environment provided by Google where you can develop gadgets for iGoogle.
To sign up for the sandbox, you need a Gmail account. Then go to this URL: http://www.google.com/ig/sandbox. Sign up using your Gmail email address. But there is a catch: If you go to the above URL again, you will be signed out of the sandbox! Then you will need to sign up again at the same URL. Just give the same information again, and you will get your sandbox access back with all your gadgets intact.
You will know you are in the sandbox when the following words appear near the top left of your iGoogle page: 'Welcome to the iGoogle Developer sandbox'.
Your iGoogle sandbox appears as a new tab on your iGoogle page. After signing up, just examine your iGoogle page to see what has magically appeared on it.
The editor in which you create the gadgets is actually a gadget itself. So to use it, you need to add it to your iGoogle page (i.e. the sandbox) in the same way as you would add any other gadget. For some reason, it is not auto-added to your sandbox even though a number of other gadgets do automatically appear there. Your first experience of the editor is just as a text box in the middle of the developer's guide, here. But you don't have to keep going back to that page to edit your gadgets.
In your iGoogle sandbox, you will have a list of gadgets displayed within another gadget called 'My Gadgets'. This is where you add gadgets to your sandbox.
For the gadgets you are busy developing, it is a good idea to uncheck the 'Cached' checkbox in the 'My Gadgets' list, so that you can see the results of your changes immediately.
When you create a new gadget and save it in the editor, copy the new URL. It is at the top right of the editor box. Then add the gadget to the 'My Gadgets' list immediately. Otherwise you may have difficulty finding your gadget again.
Save your gadget code somewhere else as well as in the gadget editor, e.g. on your own machine using a text editor like Notebook. The Google gadget editor sometimes does some odd things, especially when you are copying code from one gadget to another.
If your gadget does not display the output you are expecting, look for the basic misplaced bracket or whatever, rather than assuming it is some weird gadgety thing that is causing the problem.