The Business::ISBN module doesn't save lives, but I did get another nice note about it today.
It was only the second module I ever released, and I never expected it to help anyone. I wrote it to clean up the databases of some publishing clients. I was happy that it was able to identify most of the bad data (about 10% of the records).
Now somebody has it hooked up to a bar code scanner and it has made their warehouse staff much more efficient. A big library resources company uses it. A few other big places use it to check their databases for keying errors.
Although I like writing stuff that other programmers could use, I like it better that some of my software makes work easier for "real" people.