I don't know if you mean a program like this: http://www.poweredtemplates.com/search/translation/6/1/index.html ? Unfortunately it isn't free.
you ultimately need to know more about what the files are to find a program to open them. If you create an application you can make the file extention what ever you want and so there are certainly many very different programs that use the same file extention and added to that if you talk web pages then you can configure your server to how you want a file extention to work - a previous client wanted all his web page to end in .TV so the default page was http://www.theirdomain.com/default.tv and the contact page http://www.theirdomain.com/contact.tv etc but the server set up to act on the .TV files as per a .ASPX