In the television industry, the phrase "in the can" refers to shows that are finished but haven't aired yet.
If you post regularly to a blog, consider keeping some extra articles "in the can" too.
You'll have a buffer of work you can run if you get sick or have an unexpected stretch of unproductive writing sessions. You'll have the ability to take a long weekend or a vacation at any time without having to worry about falling behind on your work. You'll never have to operate under severe deadline pressure.
Most importantly, you'll improve the overall quality of your work, because you'll never be forced to rush any substandard work into print.
If you happen to write a piece that's particularly timely (or that's so good that you can't wait to run it), you can always put it in front of the queue and bump your buffer of work further out into the future.
How much work should you keep in your "can"? It will depend on the nature of your comfort zone and your personal discipline. At my cooking blog, Casual Kitchen, I prefer to keep about a month's worth of articles (roughly 8-9 posts) in my queue at all times.
Try building up your buffer and see if having several extra, high-quality articles "in the can" makes life a lot easier for you.