My USB hasn't failed yet but hearing all these stories a while ago, I used a toothpick to apply a small amount of epoxy adhesive (araldite) to the recessed area between the metal sleeve of the USB port and the plastic of the case. If you look at how the plug enters, you can see that there's always an air gap so it doesn't interfere with the operation of the plug.

I'm hoping that this has taken some of the strain out of day-to-day usage. It was a simple modification that didn't involve any soldering, although obviously sticking glue in your USB port carries a bit of risk.