Alfred is like Spotlight on steroids. Its an application launcher, an emailer, an iTunes controller, a weather report, a search tool, and much more. It has a free version, and a paid version that allows for extra customization.
The basic idea behind Alfred is simple: you type words into Alfred, and Alfred -- like a butler -- does what you want. But Alfred is a good butler, so it also anticipates what you want, after a short period of getting to know you. Alfred saves lots of time. For example
1. to open Scrivener, I don't use my mouse to navigate to the Applications folder or the dock. Instead, I hit cmd+space (which opens Alfred), then start typing "scrivener." By the time I hit "s", Alfred already knows that I'm looking for Scrivener. It knows this because it pays attention to me, and it knows that when I start a word with "s", I'm probably looking for Scrivener. Alfred therefore suggests Scrivener to me. I ok the suggestion by pressing enter, and Scrivener opens. That's it. Four keystrokes. Much faster than navigating with a mouse.
2. To send an email to person X, I hit cmd+space, then type "email" and the beginning of X's name. Alfred automatically matches the person to my contacts and retrieves the appropriate email address. It usually does this with only 2 characters of the person's name. I ok Alfred's suggestion and it open up my email program and creates an appropriately addressed email. [Compare with: opening the email program, pressing the 'new email' button, clicking onto the address field, filling it, etc.]
3. To search the web, I press "g" followed by the search. Alfred opens my browser and searches google.
4. I've been working on the same paper for a while, it's called "Newton's Rules". I open it almost every day. Opening it without Alfred would be a pain. I would need to open Finder, then navigate about 4 levels deep to get to the place where its properly filed. Then I would double click. With Alfred, I hit cmd+space, then "ru", then enter. Because I use the file frequently, Alfred knows by the first two letters of "rules" that I'm looking for the file called "Newton's Rules." It opens it. 4 keystrokes. [Notice that the match is on the second word of the file nae, not just the first.]
Alfred also has a variety of features that don't involve opening application or carrying out a series of steps within them. For example, Alfred remembers your clipboard history. What was that quote I clipped 3 minutes ago? I press cmd+opt+c, and I get a list of all my clips. I can turn any of these into 'snippets', which are permanently available clips. For example, the citation for Newton's Principia is a snippet for me, since I use it all the time. Check it out. More cool things to follow.