Gmail Gadget
Here is some light tech-talk: I found that it is possible to add "Google Gadgets" to the GMail interface. What needs to be done is to enable "Gadgets" in the "Labs" tab on the GMail settings page. Then a "Gadgets" tab shows up next to the "Labs" tab. Then you can provide a URL to your favorite gadget, or - in this case - point to a homegrown Gadget. I actually created my own Gadget to list my few favorite links in the GMail interface. When also enabling "drag-n-drop" in "Labs", it can be positioned somewhere in the left hand navigation bar. Below is a cutout of the GMail UI (showing my own Gadget between contacts and chat), and the Gadget code is here.