Duct Tape is the king of... stuff. And things. I mean, it would be easier for me to list the things you CAN'T do with duct tape. I've seen wallets made of duct tape, chairs and even blankets. I can't imagine they'd be too comfortable, but still it shows the versatility.
You can head over to google and find literally millions of things that can be done with this. Oh, and it also apparently is good for ducts. But NOT ducks. Don't make the same mistake I did.
These are my new favorite things. At least as far as cables and methods for tying them go. I've used these in my mine and my sisters PC builds. Tying and securing cables to increase aesthetics and airflow. For TV and video game console cables. Hell, the police sometimes use large cable ties as handcuffs.
They're just that awesome.
I recently got a ratcheting screwdriver and immediately, I loved life. I felt a love for life that I haven't felt in ever. Having the advantage of extra leverage when turning tough screws is fantastic. Something I wish I had the previous day when assembling my sisters desk.
So that's my current list for essential life tools... or tools for life, or something like that. Just a few, maybe I'll post more some other time. What are your essential tools that you couldn't do without?