The Sidereal Clock displays sidereal times and several other time standards. In digital mode it has 3 time displays and you can choose what time to show in each of them. In analog mode it shows a nice 24 hours analog clock that displays Local Mean Sidereal Time or Local Apparent Solar Time.
All the displayed times are computed from the Sidereal Clock's own timebase which is synchronized to an external NTP time server, a networked precision time reference. You may expect a precision within +/- 200ms or better if you have a stable data connection.
Local times, such as Local Mean Solar Time and Local Sidereal Time, are computed based on your true geographic longitude, obtained via GPS, if available, or via Network Location.
deciBel is a simple sound level meter for Android smartphones that uses the phone mic to measure sound pressure levels.
It displays current, maximum and minimum values in decibels, and generates 3 diferent kinds of sound level x time charts: Fast, Slow and Accumulated Exposition Times. The chart images may be saved to the sdcard and then downloaded or e-mailed.
Warning: deciBel is not standards compliant and should not be used to do professional or legal sound measurements.
See screenshots and a functional description here.