I just came across the Subversion Book. From the site:

a free book about Subversion, a new version control system designed to supplant CVS. As you may have guessed from the layout of this page. this book is published by O'Reilly Media.

At work we adopted Subversion and I really love it.  We made (in my opinion) a mistake early on by separating our projects into multiple repositories.  This makes it very difficult to handle the versioning synchronization when those projects collide.  It looks like the svn:externals property may keep us from  having to migrate to a single repository before we're ready to take on that problem.

As you can see, I've already taken away some useful tidbits.  A must read for anyone using Subversion.