Misc

timers/delays
timeout(9): Run a function after an interval, no user context required
sleep(9): Let other processes run, requires a user context
delay(9): Busy wait

Power Management
powerhook functions are called on power state changes
loadfirmware
Simple clean interface to get firmware from filesystem
cold variable
A means of telling if the system has finished booting
locking
SPL/rwlock/lockmgr/mutex

Documentation
driver man page
bus man page
install notes mention
www mention