Write a program to display directory treehouse
bash, 61 58 54 bytes

find "$1" -exec ls -Fd {} \;|perl -pe's|.*?/(?!$)|  |g'


Takes input as a command line argument, outputs on STDOUT.

Note that the spaces near the end before the |g are actually a tab character (SE converts them to spaces when displaying posts).

find              crawl directory tree recursively
"$1"              starting at the input directory
-exec             and for each file found, execute...
ls -Fd {} \;      append a trailing slash if it's a directory (using -F of ls)
|perl -pe         pipe each line to perl
'
s|                replace...
.*?/              each parent directory in the file's path...
(?!$)             that doesn't occur at the end of the string...
|    |            with a tab character...
g                 globally
'


Thanks to @Dennis for 4 bytes!