Rummaging through the Nikon D90 retail box, I came across an accessory item Nikon DK-5 which I found rather cumbersome to use when shooting people portraits. Its a piece of plastic that attempts to shield the viewfinder from glare when on timer mode shoot.
Much later, I found a neat trick to do what the Nikon DK-5 does, only totally not requiring the tedious chore of putting it on and taking it off! Just simply activate the Live View Mode when shooting with a tripod! A shutter curtain within the Nikon D90 will automatically be activated, cutting any remaining glare that sip through the glass view finder. This way, you still achieve the goal of not letting stray light confuse your exposure setting.
There's bound to be something new each day!