I'm learning the hard way that I should take my own advice when it comes to developing personal projects. As a professional software consultant, I'm very consistent about writing unit tests for my production code, if not first, very shortly after (within the hour). I've heard many a developer say "I'm busy right now, I'll come back and write those tests later." Yeah -- it almost never happens.
So what did I do with my Commons library? Wrote a whole bunch of code without tests! Now I'm paying for it - I can't bring myself to release the library without more code coverage. Right now I'm sitting at 81% code coverage, and I'm so glad that I'm working through the tests because they have exposed a few bugs.
Let this be a lesson (mostly for myself) - don't write code without tests, even if it is for your own homegrown pet project!