Spreadsheet Wiki

A spread sheet wiki is a spreadsheet that is on a server, accessible through a web browser and editable like a Wiki is.

I don't know of any open source Wiki Spreadsheets, but here is a proprietary one:

http://web.peoriadesignweb.com/spreadsheet/

TWiki (TwikiClone) has a Spreadsheet plugin - you edit the spreadsheet contents as plain text within the page. You can also attach spreadsheet files, which some peole may prefer. --RichardDonkin

Apparently you can also attach spreadsheets to JotSpot wiki pages.