Numi Calculator app for Mac you will love to use.
I barely use Alfred that much and that's mapped to the similar-but-different option+space (Spotlight is mapped to command+space by default). If this kind of functionality could extend Alfred (or Quicksilver?), there would be no question that this would see relatively regular use from me.If I need to open something, I'm much more likely to open another tab of my browser and dump queries (especially things like exchange/conversion rates) into Google. It's a shame, too, because the demo here is really persuasively showing that this can automatically do stuff I previously assumed necessarily takes an extra brain cycle or two.