In my opinion, IFTTT (If This, Then That) is the glue that binds web apps together, greatly enhancing your use of the plethora of useful, free apps that are becoming an essential part of any effective teacher's arsenal. It allows you to trigger actions in one app (or "channel") as a result of something else happening in another app/channel. The trigger - which causes the action - can be either a direct action by you (eg posting on your Blogger blog) or something indirect, caused by something you did earlier (eg the start of an event on your Google Calendar, which you added and is now starting). This is useful because often you want actions you do in one app to automatically happen in another (eg simultaneous status update on Facebook and Twitter), and although many apps allow this, not all do, so it's a useful service to have. Also, you may want actions in one app to trigger an action in another, using the services of the second app to further detail the experience. I will discuss an example of this in more detail.
I use several free apps in my teaching, with the Google Apps for Education and Evernote being the two I use most frequently. I've recently increased the number of recipes that I use to trigger actions on my Evernote channel from actions in my Google Apps; as a premium user it made sense to start getting the most out of this versatile note-keeper. I have created an IFTTT recipe which creates a new note in my Evernote "Diary" folder for each event which starts in my Google Calendar. This way I can quickly access the note (usually via my iPhone Evernote app) and record details from the event (audio, text, images etc). Although I won't always add content to the note, each note takes up so little of my 1GB per month that it doesn't really matter. I use the note to record details from the lesson that I may wish to refer back to later for purposes such as appraisal, discipline, reflections and of course assessment; Evernote allows tagging which makes it very useful for these multiple purposes.
Another useful recipe I've created will automatically create a new Google Document for me at the start of a Google Calendar event. Because I have all my lessons in my Google Calendar, each lesson gets a Google Doc created for it automatically - with the lesson details loaded into it from the calendar entry - which I can quickly link to the event and share with the class (using the Google group I've previously created). I can then enter in important points that the students need and they can collaborate on it as well, adding their observations, opinions etc. I guess it's only saving me the time if takes to create the document and add the lesson details from the calendar event, but time is precious, so any time saved is worth it.
My arsenal of IFTTT recipes is growing quickly, as I look to synchronise my web apps to simplify my web experience. IFTTT does the hard work for me. Many people will ask, "What are you giving up for this 'free' service?" The truth is that I'm probably giving up a lot of data, but there's no such thing as a free lunch and the benefits of the service are tremendous. Thanks IFTTT.