Public beta 5 of EditGrid
was announced today. Some say it tops Google Spreadsheets
EditGrid features include: Real-time update (see changes immediately when someone modifies your spreadsheet), Full keyboard navigation, 500+ functions, Import and export in all common formats (MS Excel, CSV, HTML, Gnumeric, Lotus, OpenOffice, ...), Permalinks for addressing your spreadsheets, Access control, Post to Blog, and Cross-browser support for IE 6.0+ and all Gecko-based Browsers (Mozilla, Firefox, etc).
View a highly appropo demonstation of EditGrid