I'm new to Alfred this week, I love it so far!
One thing I'm missing from Spotlight is the file searches displaying Reminders.app, Calendar.app, Mail.app, Messages.app, etc search results. I'd like to see these supported and integrated by default in Alfred, then it will be a total spotlight killer.
I've found a workflow for Mail.app (by Vero), and I'm using a simple Reminders workflow, but I'm still looking for a satisfactory Calendar and Messages search function. I haven't found a way to search Calendar yet. With messages some integration of iMessage into the Alfred contacts would be ace, the problem with iMessage is they have emails & phones, and these already do something else in Alfred! (I've currently directed all phone numbers to Skype).
