Okular - Okular is a universal document viewer based developed by KDE.
PracticePanther - PracticePanther offers CRM, invoicing, time tracking and communication solutions for law firms.
Sumatra PDF - Sumatra PDF is a slim PDF/DjVu/EPUB/XPS/CHM/CBR/CBZ/MOBI viewer for Windows.
iDempiere - iDempiere Business Suite ERP/CRM/SCM done the community way.
Foxit Reader - Foxit Reader is a free and light-weight multi-platform PDF document viewer.
PHC FX - PHC FX is a comprehensive solution that offers a wide range of functionality at any price.