Check this impressive Nikon D90 Battery Grip accessory which will give you the battery life you need for your longer trips and will provide a better stability for the camera.

With a LCD screen that displays  Date,time and also has a stopwatch function; a standard vertical shutter button with on/off switch on the grip and also provided with infrared remote sensor, this battery grip is an essential companion to our beloved Nikon D90.
This Battery grip has a built-in storage compartment that works both with the  Nikon D80and D90 battery door and tripod mounting thread, it holds one or two 2 EN-EL3e Lithium-Ion rechageable batteries and  also  you will receive an included one AA battery adapter which will allow you to use 6 AA size batteries(High Power Battery Only).

A slick appearance and superb quality I would recommend this accessory 100% .

Get this Battery Grip here for $119

nikon d90 accessories Battery Grip for Nikon D90 with LCD Timer Vertical