DLNA (Digital Living Network Alliance) is a wonderful thing. DLNA devices – such as network enabled HDTVs, smartphones, the PS3, the Xbox 360, and the list goes on – are capable of sharing all sorts of different types of media over your home network.
Unfortunately, not all smartphones are DLNA certified, but an Android/iOS app called Twonky Mobile can fix that. Twonky allows you to create a media server directly on your old smartphone, and the shared media can be played back on all sorts of network enabled devices.
Those with an old iPhone at their disposal can even go a step further. Jailbreaking your old iPhone and installing XBMC (Xbox Media Center) turns it into a full-featured media hub. Not only will it allow you to serve media files directly from your old phone, but you can also do the same with any shared file on your network. Even better, with the XBMC remote app (available on Android and iOS), you can control your fancy media server with your new phone!
XBMC even has “DJ Mode,” which plays music and allows your friends to queue their favorite songs using their own phones. With an iHome stereo (or any stereo that allows you to connect your iPhone and charge it at the same time), you’ve got the perfect party entertainment.