The Windows Phone Marketplace is ever growing (at the time of this post, there were around 60,000 apps), but sometimes the application you’re looking for is only available for Android or iOS. Sometimes this is because the vendor doesn't think the Windows Phone community is large enough to matter so they refuse to build (or even consider building) a Windows Phone version; other times it's because the vendor simply doesn't realize there is a demand for it. As consumers, the only thing we can do is be vocal about our desire to see these applications on Windows Phone.
In an effort to raise awareness, I just launched Windows Phone Marketplace Requests. This is our opportunity to request applications and show those companies just how much interest there is for seeing their application on the Windows Phone platform. This site is currently running on a free UserVoice site, so I’m a bit limited on how much customization can be done, but it allows you to easily submit application requests, add comments, and, more importantly, vote for your favorite applications to come to Windows Phone!
As I find out the status of requested applications, I will update the status of the request. If you know and have offiical communication from one of the companies indicating they will be or are working on a Windows Phone version, please let me know and I'll update the status of the request after verifying (or at least trying to verify) the information.