tree.el is a powerful navigation tool to find files and grep through directories as defined by a tree-spec. The best way to describe is to compare with TextMates find-file command and extending it to grep through all the files defined by the treespec. By default, treespec is the top-level directory chosen and one can instntly grep though the folder. If use ‘grep’, ‘xargs’ on a regular basis, tree.el can make these tasks much simpler and pleasurable. The way to define a treespec is very powerful and avoids the pitfalls of many other similar libraries. Try and have fun.

You can find complete documentation and the source on github