I broke another Macbook power adapter (old-style); the original one broke at the base, where the skinny cord meets the brick. I was especially careful to wrap the cord properly to keep this from happening again, so naturally, this one broke at the tip:
The dumb thing is that, because I didn't want to pay $80 for a new OEM power adapter, I bought a this as a used replacement off of eBay.
It worked okay until about 2 months ago, when I had to start jiggling the Magsafe connector to get it to charge. Then, about 10 days ago, it broke apart completely -- the Magsafe connector stayed in the port, and the rest of the cord broke off.
The dumber thing is that it still worked, mostly. And for about a week, I used it like this, just being careful to push it together to make the connection.
After a while, the blobs of solder connecting 120V of household AC broke off, so the jiggle trick didn't work any more. At least, not without the end of the connector getting noticeably hot, and even a little... shock-y.
Fortunately, I'd ordered a replacement. And that's the dumbest thing -- I bought another used (refurb) one off eBay.
We'll see how long this one lasts. If it goes, I suppose it'll mean it's time to upgrade to a new Macbook.