Here is another iGoogle gadget ( you can also put it on webpage ) called Response Headers

It's quite simple. It shows response status code and headers returned by server. Again, you can put it on iGoogle and access quickly.

Click here to add to your webpage.

Here is a simple Google gadget to calculate MD5 or SHA1 Hash.

Click here to add to your websitte

Click here to add to your iGoogle

Google Gadget for you site to show geographic location of visitors. Nice thing for registration pages, comments pages. You can put this Gadget on your web site.