Have you ever wished your iPhone would ring only when certain people call? Here’s how to do it:

1. Download the “Silence” ringtone here: silence.m4r
2. Copy this file into the Ringtones section of your iTunes. (Click to enlarge.)
   
   
3. Sync your iPhone with iTunes to load the ringtone.
4. On your iPhone, change your ringtone to “Silence” (under Settings -> Sounds -> Ringtone). You’ll no longer hear your phone calls.
   
   
5. For each person whose calls you still want to hear, change his or her Custom Ringtone to something audible: Click the name in your contact list, choose Ringtone, then choose something besides Default
   
   

Now you can screen calls in your sleep. Because Sunday afternoons are for napping.

For all the iPhone users out there: You probably know you can take a snapshot of whatever you see on your screen:

1. Briefly press the top and front buttons at the same time.
2. The screen will flash white and you’ll hear a “snapshot” sound.
3. A picture of your screen is now in your iPhone “Photos”.

I’ve found it extremely helpful to make screenshots, and I do it all the time. Here are a few reasons:

Remember an Interesting Part of a Podcast

If I’m driving and hear something I like in a podcast, I make a quick screenshot of the playback screen. When I get back to my computer, I can return to that spot in the podcast and take notes.

Save a Point on a Map

Sometimes I want to “bookmark” a location on the map before looking up something else. A screenshot is a fast way to do this.

Save a Website Address Without Interrupting Your Reading

Sometimes when I’m reading in Google Reader, I want to save the location of an article to read later. (I don’t want to leave Google Reader immediately because it has to entirely reload when I return.)

If you hold your finger on a link for a few seconds, a menu will popup with the address of the link. Sometimes I simply save a screenshot of the link, then hit Cancel and go back to my reading. Later I read the items I saved in my screenshots.

Screenshots can help you practice “ubiquitous capture” — capturing all notes, thoughts, and ideas, as they come to you, so you don’t have to keep them in your head.