I haven't seen a continuous version control system - one that would save changes in your code as you developed them, rather than waiting for an official check in. The changes would be saved as 'not checked in' of course, but they would be saved away for backup, and viewing by others before you actually did the official check in.
I haven't seen this, and wonder if it, or something like it, exists, and the reasons why it might or might not be a good idea.
Right now programmers think of source code control as integrating packets of code, but why not make those packets smaller and integrate continuously?