I finally got around to hanging Christmas lights this year. I bought gutter clips so I wouldn't have to permanently install anything, but I just realized that I don't have gutters along a pitched portion of my roof. The soffit there isn't perforated, so I can't hang them through it either. I did notice the metal flashing (maybe it's flashing? someone correct me if I didn't use the right term) is hung with nails underneath the eaves. Can I nail into that without worrying about moisture problems?
How about Magnetic Christmas Lights? I've never tried them, but if they use a descent magnet it would be a winner.
I've seen these before a Walmart or places like that. It looks like it would clip onto your shingles. They might be good for the short term of Christmas but I don't know how sun, wind and weather will affect their life.
Would Velcro Christmas light hooks work?
I used them one year (not this exact brand though) to good effect.
I have the same issue. I simply drive very tiny finishing nails (the ones with slightly rounded heads) every few feet and then used white wire ties to attach the light wires to the nails.
Once painted, the nails are barely visible in the summer.
(We live in an Eichler with a foam roof and, thus, don't have shingles or any kind of a real lip along the roof edge to which anything might be attached.)