In my mind, miracles are a game of statistics. If 100 pianos fall from a rooftop and crush 99 men, but miss the 100th man, is that a miracle? The last man will certainly think it was a miracle and he will tell others about the miraculous thing that happened to him. His story will then spread and become a tale of inspiration, while the other 99 stories of 'bad luck' will be forgotten. Obviously falling pianos aren't terribly common, but considering how much danger humans are in each and every day, it makes sense that some will narrowly escape certain doom. The presence of these stories doesn't really prove anything other than luck.
And, while many make claims of seeing angels or bright lights, it's entirely unverifiable. Not to mention human memory is incredibly unreliable and, when put under duress, our brains do a lot of crazy things. Some people might think that god is the easier answer, but I contend that, if miracles were evidence of god, it would paint him as a villain, indiscriminately dealing out punishments and praise, not a savior.