Just across the last one month, I have utilized four of my six lens to tackle the various sites I visited, and am finally seeing some benefits of owning the basic six lens. In total, since December (when I began using my Nikon D90), I have up the monthly shoot pace of approximately a thousand shots to approximately 1200 per averaged month, clocking at 50 shots shy of 9000 on my Nikon D90 today. There are just shots I took that will not be possible without using another lens.
I think this beast is finally being warmed up at 10,000 actuation, together with the owner to do more shoot! I am now simply toying with the idea of either using my budget to cover the remaining optical range I lack - 10mm to 18mm and 400mm and beyond or go get the soon-to-be-launched Nikon D300s. Or simply grab the Nikon D3000 together with a wide Nikkor 10-24mm and call it a day.
Its a tough decision, but somebody has to do it!