Tip of 3.5mm audio cable broke off inside iPhone. Had to use speakerphone for all calls, since iPhone thought there were headphones still attached.
The GripStick Headphone Plug Extraction Tool worked as advertised. I had to tap the tool several times to seat it in, and the the third attempt pulled out the offending tip.
Be careful with your audio cables, and bookmark the page for the tool. Running a screw into the jack or using Super Glue just didn't seem like a good idea.