SQ905 is a Mac OS X program for the photo/web cameras with the sq905 chip. These are cheap cameras (on the $20 range) that ship with a Windows-only driver, called "My DSC" or DSC(2770). Some of the models supported are: Argus DC-1510, PockCam, Che-Ez Snap, Magpix B350, Precision Mini, Vivicam 3350, DC-N130t.
Version v3b5 adds no new functionality. It simply includes all the libs that some users were reporting that were missing. So the file is bigger to download (2MB instead of 0.9MB). If the application didn't launch for you, give it a try now. If it worked before, no need to try this one.