MDSheet is a framework for the embedding, evolution and inference of spreadsheet models. This framework offers a model-driven software development mechanism for spreadsheet users. 

SpreadsheetDoc: An Excel Add-in for Documenting Spreadsheets

Documentation is an important artifact of any software product. For once, users documentation is important so they can be more productive, without the need to arbitrarily looking for the feature they want, or the need to ask a colleague. On the other hand, developer documentation allows for software professionals to more easily maintain the software.