I just had a buyer contact me on an item 10 days after the auction closed. I sent daily reminders but never threatened in any way that I would post negative feedback, report him to eBay customer service, or whatever. He finally contacted me, as I thought he would, explaining that he had been out of the country. I believe in being patient with people. Remember, an auction that may have importance to you is not nearly as important to others. I have never been burnt in over 3 years, so I believe there is something to be said for patience.
Also, whenever I list items and am going out to town, I make that known on the description of the auction so buyers are well aware as to when I will contact them.