MediaPlayer_example - this uses the great apwidgets library examples to make a simple audio player with system buttons.  This type of media player is meant for soundtracks and songs, NOT for sound effects.  For sound effects...

effects_example - this brings together a number of leads from this forum and elsewhere into a super simplified look at firing off sounds quickly with the soundPool from the android sdk.  This is the recommended method for short quick sounds that are possibly overlaid on one another.  each of the five system style buttons plays a different sound.  

These examples include the complete package with the audio files so it should work right away on your devices.  You just need to install the apwidgets library first.

I hope these are useful, and those of you with more expertise are welcome to post improved versions if you find significant errors, but I do know that these work.