I have only a few.
1) I have a kolsch that I make for my dad from time to time (he's primarily a Coors Light drinker). I sent him a case a few years ago (according to my records, brewed on 9/2/13). Well, this past fall, he calls me and asks me if it is still good. I tell him probably not and ask why. Well, apparently he had 8 left in the back of his fridge that he forgot about (he keeps his beer in a fridge in his workshop/man cave). I told him to just hold on to them and they probably aren't drinkable anymore. I popped one the next weekend when we went visit expecting it to be an oxidized mess. I was surprised to find that it wasn't as bad as I expected. It had a little metallic/carbonic twang, but was still relatively drinkable. I am holding on to the other 7 bottles for use in either a beer judging class or a tasting exam.
2) I had a British IPA, I made for a beer fest a couple years ago. It was a backup keg to the other two beers I was serving (an American IPA and a dark saison). Wound up tapping it and had about a gallon left at the end of it all. When we got home, it was late, so I just put the keg in the storage room in the garage, planning to put it in the kegerator the next morning. Well, forgot about it until a couple months later on a brew day when I was grabbing what I thought was an empty keg to transfer sanitizer. Poured it out of the keg into a pitcher to see what it was. It was still drinkable, but since there weren't many EKG IPA fans, me and another guy were the only ones who had some (it was still winter time, so it was reasonably cool for our climate).
3) Bottled some wood-aged Scotch ale as Christmas presents a year and a half ago. Wife was doing some cleaning in her craft room and found a bottle for her nephew that we didn't wind up seeing that Christmas. We drank it.