I've also wondered about this. I feel like Miracles somewhat defy the idea of evidence, as Miracles seem to cease to be Miraculous if once you can completely explain how they happened.
As far as I know, most witnesses of miracles will document what they've seen, and give a witness of it if it's happened. This was similar to how Miracles were proven in during Christ's ministry. You either believed it or you didn't.
... In the mouth of two or three witnesses shall every word be established. 2 Corinthians 13:1 KJV
I think of this quote applying not only to the word of God, but the word of the testimony of others. Multiple witnesses are usually the best thing we've got. It works the same way in the scientific world. You publish some findings, and you have some witnesses of those findings being true. With the scientific evidence you can repeat the process, and get the same results.
Miracles are a little different, as you aren't going to have the same results just doing the same things. Miracles have a lot to do with our own Faith in miracles. The conditions to make a Miracle happen follow a different system of laws than the more easily verifiable scientific laws of Chemistry, Biology, and Physics.
In the cases of people coming back to life or being healed, I suppose someone could take a measure of the condition of the person before and after, and come up with some way to prove that it was the same person. In those cases it's difficult to explain what happened because mankind still knows so little about how/why the human body really works (It's far more complex then the microchips we create that contain billions of transistors).
I really think if you're searching for evidence, but don't believe you'll find it, you may find it, but not realize it's evidence. If you truly believe in miracles, and have faith in Christ, you'll probably be a witness of them, but being a witness is evidence for you, not usually for anyone else.