MicroDicom - DICOM viewer. MicroDicom is a free DICOM viewer. Export to the most common picture formats, movie, clipboard. It is equipped with most common tools for manipulation of DICOM images.
Jim - An overview of Jim capabilities
Horos - A free, open source 64-bit DICOM medical image viewer
Insect - High precision scientific calculator with full support for physical units.
Weasis - Weasis is a multipurpose standalone and web-based DICOM viewer.
errProof - The website has a lot of useful and unique tools.