The free and open source office suite OpenOffice.org might be a killer app for many, but its inability to properly display documents created in the proprietary Microsoft Office formats hinders its widespread acceptance in multi-OS business environments with many legacy .doc and .xls files. If changing over to an open document format is not an option, try SoftMaker Office. It's no OpenOffice.org-killer, but it's a full featured office suite that has great compatibility with Microsoft Office. Sure, it costs $80, but you can increase your karma by running it on Linux.