Wireless transmitter
Bluetooth and Wi-Fi are the computer standards in wireless transmission.
But there are other means too.
Audioengine W1 Premium Wireless Audio Adapter
The Audioengine W1 is designed to connect your audio components wirelessly. Think of AW1 as a simple replacement for any RCA or 3.5" mini-jack cable to or from your iPod, Audioengine powered speakers, computer, TV, surround-sound receiver, game console, network music player - or any other product where you want to eliminate audio cables.
Audioengine D2 
The D2 sends a 24bit/96KHz PCM stereo digital stream over-the-air in a "closed-system" Wi-Fi configuration. The system's proprietary RF technology ensures data integrity with no impact on existing routers or networks. The volume control on the D2 Sender is transmitted over an entirely separate channel so there is no impact on the digital audio stream.
- Wireless bit-perfect 24/96 digital-to-analog converter
- USB-to-S/PDIF converter
- Mac or PC plug-and-play, no drivers or network setup
- Precision receiver re-clocking for low jitter
- USB and optical inputs
- Optical and analog outputs
- Burr-Brown PCM1792 DAC
Price: US$ 599
PlayGo
Wireless USB sender and receiver.
24-bit/96khz digital spdif output (TOSLINK), 192kHz option
Burr-brown SRC4192 sample rate converter
Clock regeneration for jitter-free clocking
Distortion-free volume control (256 step 0dB to -127.5dB digital attenuation)
USB limited to 16/48 but a 24/96 is planned.
A review by Michael Lavorgna
Aperion Home Audio Link $149.00
- Uncompressed digital audio transmission: 16-bit depth and 48 KHz sampling rate when using up to three Aperion HAL Receivers
- SNR: 91 dB / 85 dB when using three HAL Receivers simultaneously
- Range: Up to 100 feet
- Frequency band: 2.4 GHz
- Send unit input: USB digital or stereo mini analog jack
- Receive unit output: stereo mini analog jack
Wireless video transmitter
One day I stumbled upon this post: A guy connected two audio devices by sending the S/PDIF over a wireless video transmitter.