Everyone uses source-code control to manage versions (right?) and this provides some level of backup. There are times, however, when your local copy is out of sync with the repository. Moreover, some sandbox-type projects may not have yet ;-) made it into SCC.
EDIT: I have multiple projects in my projects directories. Not all are in current development but anyone of which might need to be "fixed" whenever a bug is found. Restoring a single, active project from SCC seems perfectly reasonable. Restoring all of the couple of dozen projects that I support from SCC seems less reasonable than restoring from a backup and syncing as necessary from SCC.
What backup strategies, other than source code control, do you use to keep your code safe?
A similar question can be found at https://stackoverflow.com/questions/38388/organization-wide-backup-strategy, but I'm more interested in hearing others' personal strategies if you happen to work in an organization that has no overal strategy. I'll provide my strategy in an answer.
My strategy is always check in, and backup the entire repository.
I never leave anything out of source control and I make sure regular backups (incremental daily, full weekly and monthly rotation) are happening and are functional.