The link below is for a web based spreadsheet written in perl which should make it in principle vo friendly on a mac. As a collaborative effort it should be open to making it same if not at present, one would hope. In part it is done by one of the people who did visicalc, the first spreadsheet and precurssor to lotus 123 and later excel.
Can one of the gurus take a look and tell us what potential it has for mac users. http://www.softwaregarden.com/products/wikicalc/ XB IC|XC
