Bubble by ktk.bz

Bubble is a free virtual bubble level for the Android platform. Hold any of the phone's four sides against an object to test it for plumb/level, or lay it down on a flat surface for a 360° level. Bubble automatically switches its orientation based on how you hold your phone. It measures angles up to 60°, accurate to within about 1 degree.

Use it to hang a poster, level a table, straighten a picture, check a wall for plumb, setup a tripod. Wherever you might need it, you can now have an accurate level with you.

Bubble can also do things that a traditional level can't do. If you need to hold it in an awkward position where you can't see the screen, turn on the beeper or the vibrate mode and you'll know when it's level. Or turn on voice mode and it will speak the angle to you.

Settings:

Show Angle: Displays the numeric value of the angle. If the phone is held flat then two angles are shown, one for the horizontal value and one for the vertical. Enable Voice: Speaks the angle out loud using the Text-to-Speech library, also available for free on the Android Market. (Not available when in 360° level mode.) Enable Beep/Buzzer/Light: All of these can be used to indicate when the phone is exactly level. Calibration: Independent calibration for each side of the phone.