A chronograph might not be a "must-have" for shooting but it's certainly a useful tool. The Magneto Speed V3 Chronograph is one of the coolest chronographs available.
Guns & Ammo's Todd Rassa and Patrick Sweeney cover the highlights of the Magneto Speed V3 Chronograph, available from Brownells, and point out a few of the key features.
The chronograph straps to the barrel of your rifle and a pair of magnets and readings are recorded when the bullet passes through the magnetic field. Unlike big, bulky units, the Magneto Speed V3 is compact and features an external LCD unit that simply attaches to the magnet unit.
Unless you try very, very hard you won't shoot this chronograph by mistake because the unit is attached below the line of fire.
And no more dead batteries from leaving the unit on -- the V3's LCD readout doesn't turn on until connected to the magnet system and turns off when disconnected. The system allows you to adjust the sensitivity of the system to accomodate for various calibers.
The unit can be attached to a suppressor allowing for further applications and, at around $400, is a pretty good bargain to boot.