One of the problems with literate programming is that it's easy to lose track of how your tangled source file (the one that the compiler actually sees) is structured. In noweb-outline-mode, you can interactively explore the tree of chunks you are creating, giving you the big picture as well as the small. Enough description; it would take more time for me to explain it than for you to just go ahead and try it out.
noweb-outline.el is currently in an alpha state (I've worked on it for only a couple of days). But it is already very useful. A nice file to use to try it out is example/wc.nw in the noweb distribution.
Instructions for use are at the top of the file. noweb-outline.el has been tested only on GNU Emacs 20.3.
noweb-outline.el version 0.0.3