Apple - Can I use a Mac Mini as an Airplay audio receiver?

Proprietary:

• AirServer - audio and streaming, Mac/Windows, $15
• Reflector - audio and streaming, Mac/Windows/Android, $15
• AirFoil - audio only, Mac/Windows/Linux, $30 for Mac/Win, $40 for both, free for linux

Open Source:

• casualShare audio and streaming, Java + NodeJS, open source
• AirStream (Ruby) - audio and streaming, source only
• Kodi - formerly XBMC, audio and streaming, Mac/Windows/Linux+, open source
• Shairport Sync - audio only (multi-room), source only (C/make); this is the not-dead version of Shairport

Dead:

• AirPlay for Totem - audio and streaming
• AirMac, on GitHub - audio and streaming, source only (Objective-C)
• AirStream (C#) - audio and streaming, source only
• Shairport - audio only, source only (C/make + perl)
• Banana TV audio and streaming, Mac, free, but only supports iOS 4.2 through 4.3.5

Both AirServer and Reflector allow your Mac to act as an Airplay receiver for audio or video. I'm not aware of an app that specializes in audio only Airplay, but either of those should do what you need.

Rogue Amoeba's Airfoil (which transmits Airplay from a Mac) is also very reliable, and includes Airfoil Speakers to receive Airplay from other sources. I recommend it highly.