[Edit] Source Code has been released for this and can be found at http://mktwp7.codeplex.com/
Zune is a wonderful application for finding and installing Windows Phone 7 applications on your phone. The other alternative is to use Market Place application in WP7 handset. If have an HTC HD2 which doesn't support WP7 officially, but thanks to XDA Developers and DarkForcesTeam, I am running WP7 on this handset with no issues.
Initially, when I upgraded, I couldn't connect to Windows Market Place and browse or install applications because of Windows Live Services Registration (which I later resolved). So, I wrote an app to resolve my problem.
What this application does is, that it allows to browse for free apps on the marketplace, and download them to your hard disk which you can later use to deploy to your handset manually (developer unlocked phone or ChebronWP7 unlocked phone). The interface is pretty simple and serves the purpose. The only pending thing is automatically deploying the downloaded application to the device, which I will leave for a later date (anyone to help me out with this).

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