There are a few things I want to change/fix and a few features I want to add to the gadget. Here they are, in no particular order:

Changes:
1. I want to change the way the gadget works to be more like the fly-out – instead of relying on the settings to tell the gadget how to display the content, I want to sniff it and display it the correct way like that.
2. Need to go over the code – I think there are cases where errors are not properly handled. I also think that there are cases where there are circular references which may cause issues with memory.

New features:
1. I want to add links at the top of the fly-out, to allow people to actually open a browser to the content.
2. Add more link types that can be in the fly-out – maybe detect any image and allow it to be displayed in the fly-out, detect youtube links and embed the movie in the fly-out etc.
3. Allow users to have “macros” for links. I can imagine having http://$server$/[…] resolving to the server the workbook comes from. Similarly the file and maybe the document library.
4. Have a mechanism in the settings window that allows you to enter arbitrary links instead of a rigid selection mechanism.
5. Use  the new SharePoint list APIs to show what files are available (so users don’t have to know the full URL by heart).

If you have other ideas, do  not hesitate to suggest them in comments!