Windows 8 like Search Contract for Search Button
It would be nice to have a SearchContract so the Bing Key could be more usefull. You could enter you search term and either press enter to bing for it or scroll down a list of search contract enabled applications blow the Textbox and tap the application you want to search. Of cause the nice images in the background wouldn't make that much sense anymore but the usabilty would be a lot better.
DO NOT VOTE ITS COMPLETED !!!
Peter Battaglia commented
This already exists, to a certain extent, in a feature called "AppConnect". For example: (this may be a U.S. specific example, but I'll try anyways) If you search for the movie "Iron Man 3", you will get a search result known as a movie "Quick Card". If you click on this result and flick to the apps pivot, you can click on any number of apps that can receive the content (Fandango, IMDb, etc). The app will launch with your search term, "Iron Man 3" populated within the app. More information can be found here:
It is in the 7.X development kit, so any third party developer can use this functionality. However, I do agree with you to some extent on this. In the above example, the original search page also returns a result for the IMDb app. However, when I click on this app result, it does not feed in my original search query -- which I believe it should. For that, I'll vote on this.
I got already Search contract implemented in couple of my Windows 8 apps. Having the same possibility in WP8 will be really great and it will improve the overall usability of the Search button a lot. Currently I use this button only for QR codes - it's not for much use here in Czech Republic.