WareLogging. * http://www.editgrid.com/ * Damned impressive. * Extensive collaboration features, including real-time multiuser editing. * Too bad it doesn't have a few more wiki-like features * Not open code, as far as I can tell, but it is built on Catalyst (I'm sending this to the next person who tells me Perl isn't suitable for "real" applications) with a Gnumeric backend. This is impressive - Gnumeric generally blazes, and the developers seem to be serious about their stats-related code. * Wide range of import and export formats, including Excel (a given) and custom XML. Exports to TeX. * Including a live, editable sheet in an Then just do {editgrid:user|spreadsheet_name} <[Brent]> Why use this instead of Google Spreadsheets? <[Brennen]> Between the two, I think this has a slight edge in in-app features - Excel it ain't, but since the backend is Gnumeric, you get a ton of functions, you can import and export from more formats (this thing does input/output of custom XML formats, and stuff like TeX output), and the interface just feels more like a full-on spreadsheet app. http://www.editgrid.com/tnc/pkchan/EditGrid_v._Google The big, clear wins are, I think the relatively fine-grained access control, the transparent ability to share read or write access to full versions of the sheet embedded in any page, and being able to pay for SSL traffic. And real-time multiuser editing of a sheet is handled really gracefully.