This tool allows you to search for subtags that have, say, ‘french’ in their description (there are currently 11), or to find out what that mysterious ‘ch’ subtag stands for (there are 2 possibilities).
Update: You can now also search for a hyphen-separated sequences of subtags, such as sl-IT-nedis and find out what each of the component subtags mean.
Alternatively, you can simply list all current language tags, or script tags, or variants, etc.
For months I’ve been wanting to write a small, Web-based tool for finding things in the subtag registry without having to work on the (for many people, intimidating) raw text file on the IANA site.
Tom Gruner created an initial tool for pretty printing the IANA list, which handled enough of the basics to allow me to use the little time I have these days to add the search functionality on top.
(PS: Some final tweaks to the code will come when I have a spare moment for things like making the expanding list more accessible, etc.)