I found a shingle in our yard the other day. Uh oh. A few years ago we had to have a roofer come out and fix a small patch of shingles that had blown off in the high winds. That thirty minute fix cost us $120. So I climbed up on the roof fearing the worst. Yup, a big patch of shingles (probably 6 sq feet) had managed to work loose and expose the underlying felt paper. Fearing another expensive repair I hunted around on the internet and discovered that fixing shingles is actually rather easy. A few hours later I was again up on the roof with a pile of shingles, some galvanized nails, a tube of roofing cement, and a hammer (as well as a pair of grippy shoes!). I ripped the bad shingles out, as well as a few more on the edges of the trouble spot, and in about an hour I had a perfect patch. The whole thing cost me less than $20 and I still have a dozen shingles left over for when the next ones blow off.
Hooray DIY!