Company name: Optaros

Founded: July 2004

Location: Boston, Switzerland

What does the company offer? Consulting and systems integration services focused on open source software.

Why is it worth watching? Optaros can be the guiding hand for enterprises considering using open source software to solve business problems. It helps customers determine where open source makes the most sense and helps put together open source components to create platforms for business.

How did the company get its start? In 2004, company founders recognized that as enterprise users became increasingly comfortable with Linux, open source would move up the stack into software. The company was founded to provide support for midsize and large companies bringing in open source business applications.

How did the company get its name? The name Optaros comes from the Latin optare, "to choose."

CEO and background: Bob Gett, formerly CEO of Internet consulting firm Viant, as well as CIO of Fidelity and Smith Barney.

Funding: $7 million from Charles River Ventures and General Catalyst in 2005.

Who's using the product? The Christian Science Monitor, Movielink, Kaplan Higher Learning.

Company name: Qlusters

Founded: 2001; contributed its management software to the open source community in January of this year.

Location: Palo Alto

What does the company offer? OpenQRM, an open source systems management platform.

Why is it worth watching? The number of open source systems-management vendors is growing, and while openQRM was made open source in January 2006, it has proved its worth in commercial deployments during the last two years. The open source platform benefits enterprise customers by offering plug-ins that let the platform hook into existing systems, whether open source, proprietary or internally developed.

How did the company get its start? Entrepreneur Ofer Shoshan started the company with the idea of creating mainframe-like manageability for commodity hardware.

How did the company get its name? Founders considered it a unique name that would be easily found through search engine queries.

CEO and background: Shoshan has more than 16 years of experience starting and managing high-tech companies and projects in Israel, and most recently was entrepreneur-in-residence at Israel Seed Partners.

Funding: $23 million in two rounds; investors include Benchmark Capital, Charles River Ventures, Duff Ackerman & Goodrich, and Israel Seed Partners.

Who's using the product? Canada's Loblaw food chain and New York City-based Tradeware Global.

Company name: rPath

Founded: April 2005; launched in January 2006

Location: North Carolina, U.S.

What does the company offer? rBuilder, an open source platform that includes a tailored version of Linux to create preconfigured, pretested application appliances that can be downloaded and deployed by enterprise users in minutes.

Why is it worth watching? Server virtualization is paving the way for simpler application deployments, in which an operating system and application can be packaged and deployed in a virtual machine for flexibility. VMware has begun offering preconfigured, prepackaged application appliances, but rPath provides an open source foundation for independent software vendors (ISV) to use in creating these appliances. Enterprise users should be watching and pushing their ISVs to take this approach, because such application appliances mean the end of complex, multi-component application deployments.

How did the company get its start? After leaving Red Hat in 2003, engineer Erik Troan was looking at ways to make open source more consumable and came up with technology to build application appliances.

How did the company get its name? Rpath is technology used in Unix systems to search for shared libraries. "We were thinking we want to let applications find the software components they need to work, which is analogous to how an operating system finds a library that it needs to work," Troan says.

CEO and background: Billy Marshall, formerly Red Hat's vice president of North America sales, with an earlier stint at IBM Global Services.

Funding: $6.4 million in January from North Bridge Venture Partners and General Catalyst.

Who's using the product? Department of Energy, Digium, Ingres.