I write software for a living, and the raw unit of measure for software source code is lines of code. You can argue what it means, or whether it's worth anything as a measure, but it is used as a measure.

I find it handy to be able to see the size of a tree of files as a line count, per file type. For example, here is the output of countlines for my Python21/Lib directory:

         ext files    lines
               142     4353
         .au     1        1
        .out     1      115
         .py   480   107433
        .pyc   150     1929
        .pyo    33      254
        .txt     1       18
        .uue     4     4858
        .xml     2      122
   ==total==   814   119083

There are no options or arguments, it examines the entire directory tree rooted at the current directory. Certain directories are skipped (ones named CVS), and certain files are ignored (ones starting with .#).

Download: countlines.py