TouchDAW

This is an amazing app. Not only does it emulate a Mackie Control Universal (MCU) but it also has various MIDI utility screens with configurable controls and a piano keyboard. A hidden feature, explained to me by the (responsive and helpful) author on his support site is that 2 MIDI connections may be established and "cross-configured" to allow it to function as a WIRELESS MIDI INTERFACE. Using a cheap PC USB/WIFI dongle, you can easily set up a wireless connection between, for example, a USB keyboard and laptop.

The recent addition of mnet wireless MIDI drivers for Windows (http://www.humatic.de/htools/mnet/download.php) makes the wireless MIDI setup much easier than it was using rtpMIDI.