Google Spreadsheets supports IE, Firefox, Mozilla, Netscape and Camino but provides no Safari support. (It worked fine on the Mac under Firefox.) Which begs the question: Do you trust a third-party web-based application with your data? Particularly Google which has had a few rather embarassing data loss incidents? On the upside, gSpreadsheets offers .xls and .csv file downloads. Downside? The formatting is pretty primitive even though the basics are all on-offer: bolding, highlighting, underlining, merging cells and more. I was even able to drag between cells to create a range for my in-progress formula.