Some great ideas on here !
The "audio TR's" reminds me of something I saw at the Grand Canyon.
I came across some reloadable MP3 files known as the AUDIO RANGER, put out by the
Grand Canyon Association.
It gives you a virtual tour of the trails, landmarks, history, etc.
In the distant future, will we even need interpretive rangers? Suppose somebody will
still be needed to maintain the restroom facilities and pick up trash.
An audio interpretation of TR's would be a breath of fresh air !!!