All of the interior doors in our farmhouse (except for the pantry) are barn doors. Really they are 7 foot solid core door panels without holes. We choose 5 panel because they looked old fashioned. We purchased galvanized barn door railing at Tractor Supply and the hardware off of Ebay. They attach on a trim board mounted over the door opening and slide freely back and forth. There are stops at the bottom so they don't open too far and rollers keep them from swinging back and forth away from the opening.
Then came the fun part, choosing hardware. Knobs were out of the question. So what do you put on them? We saw a picture in the book, The Farmhouse by Jean Larson that had exactly what we wanted but what was it? Finally, after days of searching the internet, we found them. Replacement leather handles for antique trunks. They were handmade and only $12/set! The man thought I was a total hick for putting barn doors in the house! Maybe I am, but we love them. The inside was even more challenging. You want the door close to the wall when it closes and still you need a way to open it from the inside. The leather handles wouldn't work on both sides. Then we found these ... door knob plates from Rejuvenation. The holes are just big enough to put your finger in to slide the door open and they were only 1/2" thick. Perfect!
This is what the doors look from the inside. We chose not to frame out the openings, rather we had them sheetrocked and textured. The trim wraps around so it is continuous through the house.
We do have to keep the track oiled so it doesn't make noise and we left the locks off, but the interior barn doors were a perfect fit for our contemporary farmhouse.