Livestreams often use Adobe’s Flash format and Shockwave Flash-Players to supply live content to their users. To play them on a machine that hasn’t flash installed, many pipe rtmpdump’s output to their favourite media player, making integration into home cinema systems complicated. If the URL of the stream you watch regularly does not change (e.g. a TV station’s official livefeed), you can easily play this in XBMC.
$ nano ~/Videos/Streams/MyStream.strm
While playing, clicking on the movie reel or the loudspeaker lets you set various audio and video options.