Sean Gerety has a Moleskine Spine fix that uses Friction tape:
"I’ve got an ailing Moleskine that is suffering from the fraying of the spine…I was looking around for a fix for the spine that would work. Something the same color that would blend and flex as needed. I was looking for a black cloth tape like a medical tape, however the closest I could find was 3M Brand friction tape. It’s a good strong fabric, not plastic, tape that flexes and bends…"
Read the full post at Sean’s Idea Kitchen