Interactive map of Linux kernel
The interactive Linux kernel map helps you traverse complex interconnections between subsystems of the kernel while you explore its source code. A Linux hacker, trying to track down a bug or just understand how some subsystem works, can get exhausted just trying to figure out what invokes what — so the kernel map comes to the rescue!
The map depicts over 400 prominent functions and structures divided into major subsystems. You can zoom in on any function and move about the functions graphically. The relationships among all functions are shown through connecting lines, and clicking on any function takes you to source code in the Linux Cross Reference and the collection of Linux kernel documentation.
(from Linux Mint weblog)