Everyone knows make and Makefiles? At least in Perl world everyone is using it when installing ExtUtils::MakeMaker CPAN distributions. It is present on most of the systems, so why no to find it some more usage? (read save time, ease the work)
Makefile was originally created to help compiling and linking C source code. So? So the point is that we don't have just to compile source code, but we can use Makefile-s to process any kind of dependency based files chain. Inside the Makefile there is always a target file that should be generated together with dependency files needed for generation and a set of commands to perform the task. In addition targets can be made PHONY which means that the target commands will be always executed. This is most often used for "clean" target - `make clean`, which should removed all temporary build/generated files and tidy-up the folder.
The PHONY functionality can be used beyond housekeeping do define set of commands (or a library of commands) that make sense for current folder. For development project this can be `make upload`, `make deploy` or `make ajoke` or what ever comes in handy.
The Makefile of ba.pm.org has couple of targets. Transforming .po files to .js (using po2json), .xml to .tt2, .rdf or .js (using XSLT), minifying js and css (using yuicompressor), etc. There are also a couple of PHONY targets like 'all' (to build the page), 'test' (to test the xml and site linking), 'clean' + 'distclean' to tidy-up.