We are developing back-end web services for app developers. We developed Windows Phone 7 client and working on clients for other platforms. How can we reach developers (especially Windows Phone 7) to use our product considering we don't have a budget for advertisement?
Since you are developing Windows applications are you part of Microsoft's free BizSpark program?
Microsoft BizSpark is a global program that helps software startups
succeed by giving them access to Microsoft software development tools,
connecting them with key industry players, including investors, and
providing marketing visibility to help entrepreneurs starting a
business.
You should do blogging and do technology evangelism to create awareness of your project. If you have money you can advertise too.