Buy the song on BandCamp: http://dannybrony.bandcamp.com/track/relax-in-the-clouds-rainbow-dash-lullaby-theme
Or download it for FREE: http://www.mediafire.com/?w34f3mtioverhmn
Soundcloud link: http://soundcloud.com/dannybrony/relax-in-the-clouds-rainbow

Just something I threw together in a few hours.
The first thing that came to my mind was "Clean guitar lullaby." And yes, it was very AcousticBrony inspired. Chorus + Flanger + Phaser + Vibrato = Heavenly sound.

Not really the best I could have done on an instrumental but I think it actually turned out pretty well. I was actually just fiddling around with pedal effects and chords and suddenly got this song. It's a short song, though.

If you liked the song then give it a like and/or favourite and be sure to click the subscribe button on the YouTube page.
Also, follow me on these sites.
Twitter: https://www.twitter.com/DannyBrony/
Tumblr: http://dannybrony.tumblr.com/
Facebook: https://www.facebook.com/DannyBrony
BandCamp, please donate here: http://dannybrony.bandcamp.com/

UPDATE:
Featured on Equestria Daily (9/7/2012): http://www.equestriadaily.com/2012/09/instrumental-music-inescapable.html
This song is part of an upcoming project! STAY TUNED!