I like AUTOMATION. By that I mean I enjoy working on tasks that are suitable to batch processing. By building an automatic solution once I can solve the problem hundreds or thousands of times later on, with little or no effort.
I'm not really that good with Bash or Perl, but I'm so much better than the people around me, so when I batch process a thousand files, people think it's magic!
Today I've been working on my module - the one I talk about all the time! I've been adding tests, and fixing obscure problems that I've spotted. I really like the power that testing brings, you tinker with your code, run tests, and if you broke something by accident you find out pretty sharpish. I've even got a little CMD script to automate the build and test, not perfect, but useful on Windows, where I always want to type "make" not "nmake".
Somewhere recently, either here on Perlmonks I saw a script that scans a module looking for methods not documented in the POD, can I for the life of me find it! That would be useful now, I don't like loading things to CPAN, only to load them again a day or so later when a critical bug is found!