First let me say that you can’t always see the “dust” on the sensor with your eyes. Many times the only way to see the spec(s) on the sensor is to take a picture of the sky at a small (large number) aperture.
Oscar developed this method of cleaning the sensor. I have tried it and it works well. Of coarse if you decide to try it you do so at your own risk.
Michael Reichmann has written this article about sensor cleaning.
Here are some threads concerning cleaning
Read through this thread
Here’s a long thread
Places to buy supplies
The Filter Connection
Photographic Solutions Inc.