Originally Posted by retched
If you can't find one you can turn on the in game timer and type in when each buff/objective was taken.
Blue/Red -- 5 mins
Dragon -- 6 mins
Baron -- 7 mins (4 min buff duration)
Ex: (11:04 (player name /champion name): 17:04 dragon
Gotta agree with Retched here.
It's better to just memorize the respawn times of the buff/objective camps. Eventually, you'll also develop an innate sense of when something will respawn. (ex. a gut feeling that dragon or buffs will respawn since you took it earlier w/o looking at a clock/timer).
Support players and junglers are... encouraged to help state when the buffs/dragon/baron will respawn.
A good tip on baron respawn: the buff last 4 minutes. so you can look at the buff to know exactly when it will respawn (each 1/4th of the buff is one minute). When the buff expires, there are 3 minutes left until baron respawns.