I've been working on a Subversion post-commit hook that will send me an e-mail when a user checks in some code to a repository. In order to send an e-mail from the post-commit script I needed a command line tool that would let me send an SMTP message from my batch file.
Fortunately for me, I stumbled upon SendEmail by Brandon Zehm.
This program is chock-full of features and is the perfect companion for Subversion for Windows installations. I can also see this being an extremely useful general debugging tool as it as you can create some really complex e-mail scripts.