I had this idea already in February - see this thread for a 'concept':
http://talk.maemo.org/showthread.php?t=43362

Back then there didn't seem to be too much interest

EDIT: Pasted the idea from my older post below:
***
Is it possible to capture the pressing of the 'space' key while on the desktop view? Currently when you start typing the phone starts searching through the contacts but hitting 'space' does nothing.

This could be used to launch an application. A dream app would be a kind of quick search / applauncher.

Use cases as follows:

* while on desktop - hit space
* text box opens to the bottom of the screen
* start typing and the app starts filtering your installed applications whose name matches the string you are typing

* launch an app from the list
OR
* hit 'search' (button somewhere - local search or launch Google etc.)
OR
* execute a script / command

User definable keywords would be nice for the searches and triggered functions. The TouchSearch widget has a nice UI - almost perfect for this case.
****


-markus