The Raspberry Pi makes a great a great media center running applications like XBMC but the audio output on the Pi is a little basic. element14 have announced a new £24 add on audio board for the Raspberry Pi which is going to bring high quality audio to the Pi. The board fits on to the Pi via the P4 pins and uses a Wolfson audio processor which supports 24 bit / 192Khz via a 3.5mm or S/PDIF connection. You can also record with it as it has S/PDIF and 3.5mm inputs. There are output for a speakers via a 2W Class-D amp and an on-board MEMS microphone.
There have been other audio solutions for the Pi but I love the idea of the integrated board and for only £24.01.
More info and the purchase links at element14