This is Haewk's "Hawks MP3 player" but i have changed the place of the buttons and added a menu in the channel section so if you right click in the channel section "MP3 Player" will be there.
/song : shows what your listening to
everything else is pretty self explanitory

V.1.1 Update - This is a very minor change but i changed menu channel to menu * which makes it so you can right click any window to get the list with "MP3 Player" in it. :)

V.1.2 Update - My freind had used this, but he said it didn't work, so i just changed "mp3" to "mp4" i hope it will work, and if it doesn't comment below that it doesn't (P.S. With it being mp4 you can use it with other mp3 dialogs)

V.2 Update - With Version 2 i gave it a, kind of new look, i put buttons in boxes, Text at the bottom showing credits. Check it out for yourself! (spoiler: i'm going to try to put in an "add directory" to my dialog next update)

V.2.5 Update - ^Neptune said that the MP3 looked horrible so i moved some buttons up and made the list shorter (happy? :p). Also i fixed the del file button, so it acctually deletes files from the MP3 instead of doing nothing.

V.2.6 Update - I decided that the close button was useless scince it's close to the 'X' button anyways. so i decided to change it into a 'Check For Updates' button. This will make it easier to come back here and see if i've improved it.

V.3.0 Update - I moved around all of the buttons to make the dialog smaller .i also changed add and del to ADD and DEL for clear reading. Make sure to give ideas so i can get more updates out.

dialog mp4 {
  title "MP3 Player V.3.0"
  size -1 -1 350 190
  option pixel

  box "Music Play Options" 12, 210 45 138 94
  button "<<", 2, 215 110 60 25 ok tab 11
  button "||", 3, 215 60 130 25
  button "", 4, 215 85 60 25
  button "|>", 5, 285 85 60 25 
  button ">>", 6, 285 110 60 25
  button "Check For Updates", 10, 215 140 130 25

  list 7, 1 0 208 170, hsbar vsbar extel
  box "ADD/DEL file" 11, 210 1 138 45
  button "ADD File" 8, 215 15 65 25
  button "DEL File" 9, 280 15 65 25
  text "|Haewk's MP3 player Edited by RagBot|" 14, 75 170 200 25
}
menu * {
  MP3 Player { player }
}
on 1:dialog:mp4:sclick:10:{ url -an http://www.hawkee.com/snippet/4369/ }
on 1:dialog:mp4:sclick:8: {
  set %song1 $sfile(/)
  write playlist.txt %song1
  did -a mp4 7 $nopath(%song1)
}
on 1:dialog:mp4:sclick:9: {
  set %del1 $did(mp4,9)
  set %del2 $did(mp4,7).sel
  write -dw [ $+ [ * [ $+ [ %del1 [ $+ [ * ] ] ] ] ] ]  playlist.txt
  did -d mp4 7 %del2
}
on 1:dialog:mp4:init:0: {
  set %number 1
  :next
  set %song2 $read(playlist.txt, %number )
  did -a mp4 7 $nopath(%song2)
  inc %number 1
  if ( %song2 != $null ) { goto next }
}
on 1:dialog:mp4:sclick:5: {
  if ( %pause == on ) {
    set %pause off
    splay -p resume
  }
  else {
    unset %play1
    unset %play3
    set %play1 $did(mp4, 7).seltext
    set %play2 $did(mp4, 7).sel
    set %play3 $read(playlist.txt, w, * [ $+ [ %play1 ] ] [ $+ [ * ] ] )
    splay %play3
    set %listening $nopath(%play3)
    inc %play2 1
  }
}
on 1:MP4END: {
  set %play3 $read(playlist.txt, %play2)
  splay %play3
  set %listening $nopath(%play3)
  inc %play2 1
}
on 1:dialog:mp4:sclick:4: {
  splay stop
}
on 1:dialog:mp4:sclick:6: {
  splay $read(playlist.txt, %play2)
  set %path $read(playlist.txt, %play2)
  set %listening $nopath(%path)
  inc %play2 1
}
on 1:dialog:mp4:sclick:2: {
  dec %play2 1
  splay $read(playlist.txt, %play2)
  set %path $read(playlist.txt, %play2)
  set %listening $nopath(%path)
}
on 1:dialog:mp4:sclick:3: {
  set %pause on
  splay -p pause
}
alias song {
  if ( %islist == me ) {
    describe $chan %text %listening
  }
  else {
    msg $chan %text %listening
  }
}
alias setup {
  set %islist $$?="When you say what you're listening to, shall it be in /me or /say. (me for /me and say for /say)"
  set %text $$?="And what do you want to say? Example: Now playing: or is listening to"
  echo ok, type /song to show what song you're listening to
}
alias player {
  dialog -md mp4 mp4
}