I've said it before, but there are few things quite as annoying (or embarrassing) as having your smartphone go off at a time where it just shouldn't happen. Imagine a nice, intimate evening with your significant other; you dim the lights, snuggle up, and "this classic" comes on. Or, your phone goes off in a meeting, and your boss gives you that look.
To combat these issues, Android dev zevele created Ringer, which he actually started for his wife who was missing her old ringer modes. Ringer is a bite-sized app that gives users the ability to customize how and when your device rings.
This app isn't available on Google Play yet, but you can download the latest Ringer APK from zevele's thread on XDA. Make sure you have Unknown sources enabled in Settings -> Security -> Device Administration before trying to install.
Once you've done that, you can install the app and select your installer of choice and hit "Just once" (it doesn't really matter which one you choose, but "Always" will default to that option for installing APKs).
Although Ringer will not take up a lot of space on your phone, it ' full of features and user settings. You can set Ringer to start on boot and designate "Active Mode," or when Ringer is active (silent or vibration).
Beyond those general settings, you can set up Auto-Ringer preferences which can be based on Calendar events and automatically turn on silent mode based on the direction the device is facing, either with the screen up or down.
You can also check out the advanced settings and change the default beep or ringtone. If Ringer is active and you choose an actual ringtone, your phone will ring once. That means if you are in a meeting, your ringer will go off, but just once. The suggested default is the beep notification, which is much more subtle. You can also, just set it to vibrate.
Ringer is a great app to help those double-check themselves. You never want to go into a place unsure of what your phone may do. With the option to customize the ringer around calendar events and meetings, or set Ringer to be on watch constantly, you will save yourself a lot of grief.