First of all, I didn't even know there was an official name for recycling an article. Turns out there is: "repurposing" an article is what the pros call it.
Secondly, although I had some vague thoughts about recycling my work, I hadn't done anything about it. Oh, I rewrote some fiction pieces, making them shorter for flash, or making them longer when I gave up on the "flash" idea. And I save almost every word I've ever written because you never know when you might need a scathingly brilliant turn of phrase. But "repurposing" a non-fiction article? Uh, no.
But when I read how an article could be reworked to fit several different markets, I had one of those Eureka! moments. Now, I find myself looking over old pieces, wondering where I can send the "new and slightly re-purposed" article off, thereby adding to the Cathy C. Hall Fortune-O-Meter.
What I'm trying to say here, grasshopper, is hold on to your articles, whether you've sold them or not. You never know when you can recycle some of those ideas to fit another market. And don't sit around thinking about it. It works better if you actually do something.