Great Tip Sisil
However the Vuforia SDk isn't available on Windows Phone as yet. but if you are doing it on Android / IOS then yes it looks like an excellent choice.
It is also available on Windows but unsure yet if that will work on Win 8 as it uses a lot of Native support for the video stream (will try a hammer with it)
The thing that impressed me most about the framework is that there is an extension for Unity with it, this is truly amazing if frameworks like this make themselves available to other multi-platform products as well.
Link if anyone wants a further read - http://bit.ly/MCKnZW I may do a follow up article on this.