Warning - this article may be dangerously confusing to non-programmers
The Google Docs product provides several systems for programmers to create custom applications. The spreadsheets component in particular includes specific APIs to create, update and read spreadsheet data. These APIs allow you to develop custom standalone applications and new features, which you can make available to all Docs users. Create anything from a simple custom report to a more complex analysis of data held in a spreadsheet. Many developers are even using spreadsheets as simple hosted databases.
The APIs available in Google Docs spreadsheets include:
Spreadsheet Gadgets:
Add new features to the spreadsheets editor or create a custom representation of spreadsheet data. A spreadsheet Gadget is presented as a floating window on top of the spreadsheet, and can be "published" to other web pages such as iGoogle. Today, the spreadsheets Gadgets API is just a combination of the Google Gadgets API and the Google Visualization API.
- Getting Started with Spreadsheet Gadgets
- Spreadsheet Gadgets Developer Guide
- Sample Spreadsheet Gadgets
Google Data API:
Read spreadsheet data as a feed (Atom/RSS) or create complete applications which read and write spreadsheet data. The Doc List API allows interaction at the file level (upload, list, search) while the Google Spreadsheets API allows interaction at the sheet, range, row and cell levels for querying and editing.