I recently had a big spot show up in the same place on all my pictures. I have always wondered what I would do if this happened. I have read about the different fancy products that you can buy to clean your sensor but haven't purchased any. Before I did anything I Googled how to do it and found out that there really wasn't anything to it. This is what I did and it took me about 60 seconds to fix my problem.
#1 Charged up my battery so it would be fully charged. I do not know the reason for a full charge but that was in the instructions
#2 Went into my menu and locked up the mirror
#3 Took the brush part of my lens brush blower combo off
$4 Removed the lens from the camera
#5 Held the camera with the opening facing down and used the bulb blower part of my lens cleaner to blow air into my camera making sure not to touch the sensor or anything else
#6 turned the camera off so that the mirror would drop back into place
#7 Put the lens back on, took a picture and problem was fixed
This whole process to about a minute to do and my camera now has clear pictures again Bottom line is that it was very simple and easy to do and required no fancy products to complete the operation. Fast, easy, and effective is a great combination.This was done on my Nikon D80 but should work just as well on any camera make. I hope this may help some of you that have the problem and were apprehensive about doing something about it, Jeff