The swiss army knife of module editing
When developing a module, there's a lot of boring, monotonous work involved: boilerplate code, makefile editing etc. gr-modtool is a script which aims to help with all these things by automatically editing makefiles, using templates and doing as much work as possible for the developer, such that you can jump straight into the DSP coding.
Note that gr-modtool makes a lot of assumptions on what the code looks like. The more your module is custom and has specific changes, the less useful gr-modtool becomes.
http://gnuradio.org/redmine/projects/gnuradio/wiki/OutOfTreeModules