Have you ever turned off sound on phone before going to sleep, and forgtot to turn it on in the morning?
Or you need to off the sound at class times?
In any case this app is for you. Just specify the time frame for "silent mode" and press button. That's all. Your phone will be muted and unmuted or regular basis in specified timeframe. Application works as service so you can turn-off or reboot your phone without having to start "Silent Droid" again.
PS: Developing for Android is fun, but it has some negative sides too. Biggest one is amount of devices and OS versions. I'm trying to test apps on different phones and emulators, but there is always will be a phone where my app does not work for some reason, so if you encountered any problems - feel free to mail me - feedback is always appreciated.