Company name: Sahana

Founded: January 2005

Location: A community-driven project hosted on SourceForge.net and sponsored by the Lanka Software Foundation, a Sri Lanka-based nonprofit committed to promoting open source software development.

What does the company offer? A secure Web portal that includes applications used to coordinate and collaborate during relief efforts following disasters.

Why is it worth watching? The Sahana Project illustrates the humanitarian benefit of open source; it can be useful to large organizations dealing with the aftermath of disasters.

How did the company get its start? The project was launched following the Asian tsunami to create a flexible, customizable framework of pluggable applications free from the licensing worries of commercial software.

How did the company get its name? Sahana means "relief" in the Sri Lankan native tongue.

Who's using the product? Used by the government in Sri Lanka during the Asian tsunami and the government in Pakistan during the 2005 earthquake. Sarvodaya, a charity organization in Sri Lanka, is predeploying Sahana to manage its disaster response.

Company name: WSO2

Founded: August 2005

Location: Boston, London, Sri Lanka

What does the company offer? Tungsten, an Apache-based open source application server built from the ground up to handle Web services. The company is planning to roll out a line of Web-services-focused, Apache-based middleware, with its Titanium Enterprise Service Bus due for release soon.

Why is it worth watching? Most existing middleware was designed to handle transaction-heavy, Java-based applications, so Web-services capabilities had to be layered on top. WSO2 is building its middleware specifically for Web services and using an open source model to encourage community involvement in its development.

How did the company get its start? Former IBM and CA executives decided the current approach to handling Web services - putting a layer in front of a Java-based platform to perform Web services - was not the best approach. The company was launched to create middleware that puts Web services first.

How did the company get its name? The idea behind the company was to reinvigorate, or oxygenate, Web services, thus WSO2 stands for Web services and oxygen.

CEO and background: Sanjiva Weerawarana, formerly at IBM Research, where he co-authored several Web-services specifications and became the driving force behind IBM's Web-services strategy.

Funding: $4 million from Intel Capital.

Who's using the product? Undisclosed; targeting financial services.

Company name: Zenoss

Founded: August 2005

Location: Maryland, U.S.

What does the company offer? Open source network and systems-monitoring software.

Why is it worth watching? Zenoss provides a management package that lets users manage and monitor everything from network devices to servers to applications to environmental conditions. The free software should be of interest to midsize companies, which haven't had access to this functionality in the past because of cost issues.

How did the company get its start? Erik Dahl, who spent 15 years in IT management at firms such as application service provider Usinternetworking, began working on management software in 2002 after years of frustration working with the big enterprise suites from companies such as BMC, CA, HP and IBM.

How did the company get its name? Zen plus OSS [open source software]. "We are bringing the Zen of open source to IT management," says Bill Karpovich, co-founder and CEO.

CEO and background: Bill Karpovich, who previously held executive positions at companies such as Usinternetworking and Digex, as well as time with Accenture, where he focused on technical architecture of next generation information systems.

Funding: $4.8 million in August in A Round led by Boulder Ventures and Intersouth Partners, previous funding by private investors and the state of Maryland.

Who's using the product? Commercial clients include Mercy Hospital of Baltimore and CableVision of New York.

Company name: Zmanda

Founded: September 2005

Location: California, U.S.

What does the company offer? A commercial version of the open source AMANDA (Advanced Maryland Automatic Network Disk Archiver) backup utility software, as well as services and support for the software.

Why is it worth watching? By basing its products on open source software, Zmanda can offer a cost-effective data protection alternative to costly proprietary offerings from companies such as EMC.

How did the company get its start? Founders saw the benefits of open source and the success of the AMANDA project that had launched in 1992 and wanted to provide enterprise-class services around it.

How did the company get its name? A play on AMANDA - providing storage backup and recovery from A to Z.

CEO and background: Chander Kant, who previously founded and ran LinuxCertified and was an executive at Veritas and SGI.

Funding: $5 million from Blue Run Ventures and Canaan Partners

Who's using the product? Cycorp, Berkeley Design Automation

Senior Editor Deni Connor contributed to this story.