Some Nimisis software that's been popular with star gazers and academics is Exposure, which makes long exposure images with a webcam. There's a new version out now which allows users to set where to save the resulting image and also what format, i.e. compressed or uncompressed.
To download go here.
Version 2 of Webcam Exposure is out! Improvements include support for high definition cameras and some minor bug fixes from version 1.