I forgot to mention a while back that I fixed a leaky skylight in our house. I must admit that this has been the biggest "homeowner" challenge to date. After several tries and a *LOT* of money spent on various attempts I finally got it.
I ended up having to remove the roof shingles around the top half of the skylight. Once that was done I placed new tarpaper, reflashed the skylight, and added another layer of tarpaper over the flashing. Finally, I could put all new roofing tiles back in place. As it turns out, the leak was due to a small hole in a shingle and tarpaper about 3 feet above the top of the skylight. Water was leaking between the wood and the tarpaper and into the skylight. It was good that I tackled it as soon as I saw the watermarks around the skylight. None of the wood was rotted or warped.
As it turns out, the whole skylight was improperly installed. The leaky shingle was just the "canary in the mine". Eventually we would have had far worse leaks. I was amazed to find out that all that was protecting the roof this whole time was a flimsy piece of tarpaper around the skylight. The flashing simply wasn't doing its job. At this point though, the problem has been fixed in "industrial" fashion :-) It even passed a direct assault by a "hose monsoon".