To my opinion the new Quick Search Box is a greatly under appreciated feature.
Apart from searching, it can also be used for commands.
This allows so many new possibilities I would even call it a new generation of widgets!
It can be used for inputting new data rather than outputting existing data.
The main benefit is that a common input task no longer requires navigating through an app.
Just start typing into the home screen to open the QSB and "submit" into an app by selecting a suggestion.
In many situations an app never needs to be used at all!

So far 4 apps have been developed to demonstrate this use:

* Search Calculator - Type a calculation into the search box and get the result as a suggestion. no need to click the result.
* Search Tweet - Type some text into the search box and select the "send tweet" suggestion to twitter the text through Twidroid.
* Search Calendar - Describe a calendar event like "sat 9pm to 23.30 party time at my place". Select the "create calendar event" suggestion to store it to the calendar. No need to open the calendar app.
* Search Url - create a shortcut for a url and define how to insert the search query into the url to easily launch any app for which a protocol is defined

more info and screenshots
* http://www.cyrket.com/search?q=qsb
* http://android.arnodenhond.com/apps/qsb

I think many more apps could be optimized in a similar way.
Which are they?

I added another QSB tool: Currency Converter
It uses live data from Google Finance to convert between 64 currencies.
You can set your default input currency and preferred output currencies.
However it is also possible to do other conversions by typing the currencies into the qsb along with the amount
It works pretty good