Salesforce.com has launched a $25 million investment fund to encourage the development of new applications using its Force.com hosted development platform.

The fund, created with investment companies Bay Partners and Bessemer Venture Partners, will make investments of $500,000 or more in startup companies using Force.com, the companies announced Monday.

Salesforce.com refers to Force.com as its "platform as a service." It allows companies to build add-ons to Salesforce.com's hosted CRM software, or entirely new hosted applications, using prebuilt database, logic, and workflow services from Salesfore.com.

The goal is make it easier to build hosted applications by letting Salesforce.com provide the underlying infrastructure services.

Last month, Salesforce.com released a new part of Force.com called Visualforce, a tool for creating user interfaces in HTML, AJAX (asynchronous JavaScript and XML), or Adobe Systems' Flash.

The tool is valuable because it lets companies build applications that don't have to have the same look and feel as Salesforce.com's own applications, which wasn't possible before, commented analyst company Ovum.

Salesforce.com didn't say how much each company is contributing to the investment fund, only that they will invest about $25 million over three years. Salesforce.com will act in an advisory capacity, it said.

Bay Partners has already invested in companies that list their applications in Salesforce.com's AppExchange marketplace, including Eloqua, which makes demand generation software, and Xactly, which develops sales management software.