Over the last six months I noticed my phone getting harder to charge. The cable would only stay in at the prefect angle, and if it fell out I would wake up in the morning to a phone that wasn't charged. I was finding it more and more frustrating, and I was worried that soon I wouldn't be able to charge my phone at all. Replacing the cable helped a little, but not much. As I was looking online at replacement micro usb ports [1], however, I saw a suggestion that I clean the port. Using a toothpick (non-conductive, but I took out the battery anyway to be safe) I removed an incredible amount of fuzz and lint from the port. Now the cable fits well, and I'm way more relaxed about charging the phone.

[1] Remarkably cheap, assuming you're up for installing them yourself and risking breaking your phone.