VMPK for Android (net.sourceforge.vmpk) on Google Play
VMPK (Virtual MIDI Piano Keyboard) is a MIDI Controller emulated by software. It produces MIDI events, which can be received by other compatible devices like MIDI Synthesizers to produce sound. This application already includes a MIDI Synthesizer, in addition to a mechanism for transmitting MIDI events by the network that can be received by computers connected to your local network, using either Ethernet or Wireless interfaces.