I have a D700 and D300s and have, I suspect, typical issues with dust on the sensor. I've tried cleaning then myself with a blower brush and with swabs designed for this purpose. It seems I just rearrange the dust without removing it all. So far, my only effective solution has been to take it to a service centre and pay $50 to have it properly cleaned.
Would sure like to hear from others who have more cost effective solutions to this problem.