Here is a list of my favorite few.
Securing computer cables. It is great for splicing wires because it is wider and more sturdy than black electrical tape. Emergency luggage patch. Repairing and marking your guitar case. Hide a key under your fender. Emergency hose repair. Holding the batteries in your remote control. Tape an extra desk key under your desk. Remove those long ear hairs the come with middle age (ouch!).
Extra bonus. Add a few years to that favorite book by re-enforcing the ragged binding. What are your favorite uses? Reg Adkins writes on behavior and the human experience at (elementaltruths.blogspot.com).