Google plans to roll out enhancements to its online spreadsheet program, including the ability to display data in new ways using lightweight "gadgets" and to notify users via e-mail when data is changed.

The enhancements, expected to go live either late Tuesday or early Wednesday, will be extended later to the other Google Docs components: the word processor and presentation applications.

[ Read related news about Microsoft's recent moves to spur interest in its Web-based software. ]

The gadget feature will let third-party developers and Google create new features for the spreadsheet application in a componentized way, said Jonathan Rochelle, senior product manager for Google Docs.

"If we have a new idea for visualizing data, we can create that as a separate feature that can be pushed out to users of Google Docs' spreadsheet," he said.

For example, a gadget could be created that takes data from a spreadsheet and presents it visually on a map or in charts that can be displayed in Web sites that support inline frames, such as the iGoogle personalized home page, he said.

"We're finding today spreadsheets being used more and more as a foundation to publishing information on Web sites," Rochelle said.

The gadgets will access spreadsheets via a visualization API, designed to let developers quickly identify a range of cells whose data they want the gadget to use or render graphically, he said.

Meanwhile, the new notification feature will generate e-mail messages to users who collaborate on a spreadsheet, alerting them of changes to the document, including who made modifications and what changed.

The notifications, which users can configure to receive once per day or every time a change is made, also include a link to the spreadsheet, where the modified cells will appear highlighted, Rochelle said. "It supports the collaboration and makes it stronger," he said.

Google didn't say on Tuesday when the enhancements would be made to the other Google Docs programs.

Google Docs is a free suite of Web-hosted applications that is considered a rival and a complement to Microsoft Office, the dominant office productivity suite. Unlike Microsoft Office, which is designed to be installed on PCs, Google Docs lives on Google servers and is accessed via a Web browser. While Microsoft Office has more features, Google Docs has gained attention because it allows people to collaborate on documents and jointly edit them.

Microsoft has recently been making moves to make its software available via the Web, including enhancements to Office Live Workspace, which is still in beta, or test, mode.

People can sign up for Google Docs only, or they can use it as part of a broader collaboration and communication suite called Google Apps, which includes other components such as Gmail, Google Sites, and Talk.