If you're trying to decide on a background track, wedding reception picks or other crucial tunes, you don't have to be in-person to get instant reactions. Listening Room lets anyone upload tracks for playing in real time to anyone with the link.
One person heads to Listening Room, creates a room with a name, then sends the link, or just the name, to anyone else they want to be listening. Click the record player, pick an MP3 from your system, and it starts playing as it uploads. Everyone else "in the room" hears the same track, too, at roughly the same time. You can chat about the track in the right-hand with your name attached, or post the link publicly and let folks jump in and heard you DJ. It's a bit safer from the usual label/lawyer/licensing issues, too, as nobody can download the tracks, or even adjust their playback.
Listening Room is a free service. On an outside guess, it's also a passion project, and it might get overwhelmed by traffic at first, so give it some time if it doesn't respond.