I researched this out quite a bit before I bought my current rig. I didn't want to carry the two lens kit that comes with the d5000 so i settled on the 18-105 mm afs ed. it was a good choice. its sharp contrasty and relatively small and lightweight. with the 1.6 crop factor its actually quite long and since its so sharp, cropping is a real choice.
I read less than stellar reviews of 18-135 and its starting to hit real money to me.
I have heard really good things about the 18-200 that ken rockwell loves so much but that was just too much money for me. if money is no object and you really think you need the longer reach i would get that.
>Check out the Tamron AF 18-270mm F/3,5-6,3 Di II VC LD >Aspherical Macro. > > They have a 80 dollar rebate on that lens right now too, it will go off the rebate soon. I bought one at amazon.com for 599 with the rebate almost 500, it's no longer than the nikon 55-200mm a bit bigger around and the camera and lens weighs in at around 2.8 lbs.
Welcome to Nikonians! The screw in accessory filter type lenses will severely degrade IQ (Image Quality) and are not worth the price however low it might be. One would be better off using the kit lens and cropping the image. Good Luck and Enjoy your Nikons!