Pyspread - pyspread is a non-traditional spreadsheet application that is based on and written in the programming language Python.
EtherCalc - EtherCalc is a web spreadsheet.
Gnumeric - Gnumeric
Microsoft Office Excel - Microsoft Office Excel is a commercial spreadsheet application.
XCubes - Multidimensional spreadsheet for financial simulation, planning, reporting, marketing analysis etc.
LibreOffice - Calc - LibreOffice Calc is the spreadsheet program you've always needed. A fork of OpenOffice.