This sounds cool on an accoustic or an electric with a clean tone 
(or chorus).

This is a partial barre chord. Notice the difference with a 
traditional D chord. Just use the same chord, but slide it up the 
neck to create other chords, letting the D and sometimes A string 
ring open.

            D
          E|-------|---1---|-------|-------|-------
Guitar    B|-------|---1---|---2---|-------|-------
 Neck---> G|-------|---1---|-------|-------|-------
          D|-------|-------|-------|-------|-------
          A|-------|-------|-------|-------|-------
          X|-------|-------|-------|-------|-------

Same trick, using the open E shape. This will sound very full at the 
3rd, 5th and 7th fret.

            E
          E|-------|-------|-------|-------|-------
Guitar    B|-------|-------|-------|-------|-------
 Neck---> G|---1---|-------|-------|-------|-------
          D|-------|---3---|-------|-------|-------
          A|-------|---2---|-------|-------|-------
          E|-------|-------|-------|-------|-------

Being able to play these with a combo fretted/open strings allows 
you to hold the chord and add filler notes to play a melody.