There are probably free apps that will do the same thing, however, this one tested well and performs as expected, so I will recommend it to you.

Search the Android Market Place for “WavPlayer”, it is by Dennis Lockshine.

https://market.android.com/details?id=com.dkro.wavplayer&hl=en

 People also say you can try Remote Wave Free

Once installed, open an email with a voice mail (WAV) attachment and you can then PLAY. When prompted, select the WAV Player app…