Something I fell upon in someones Facebook picture library but never seen them before. Looks interesting.
 
http://www.gizmag.com/the-rock-lock-helps-protect-your-guitar-from-thieving-hands/16732/pictures#1
 
For some reason I can't get the company web site to load to see if there is a bass version but they seem to be $49.95 from strings and beyond.

Looks like the cable lock that we bought for my son's brand new bike in High School.  It was stolen the first day.  The bike shop people told me bolt cutters go through these like a hot knife through butter.  Of course if you attached the other side to your ankle, it would probably prevent theft just fine.
 
Bill, tgo

Somehow I can't see much need for something like this. Best protection for an instrument is to make sure someone has it in their field of vision at all times.  
 
I would be way more concerned with an instrument getting stolen when checked as baggage on a flight than stolen at a gig. Or getting swiped from a parked car even if left in the trunk.

Guess the only selling point is that if someone is looking to lift your guitar from a gig, they probably aren't carrying bolt cutters.

My guess this is one of those items that keeps an honest man honest but won't be much deterrent to someone dead set on stealing the guitar. So for a bar gig break or something like that it would probably be ok. I still think having my wife on guard duty is a better deterrent and gives me some company for the drive to boot.  
 
Bill, I had a similar event as your son's when I was in high school. I had just returned from its first weekend bicycle trip and stopped by the store to pickup a couple of things before going home. Came out about ten minutes later and the bike was gone. That's when I learned quick release hubs aren't just for changing tires.
 
 
Keith

Advice given to me by several professional thieves during the time I worked in a prison in the early 80's:
 
If I know it's there and I want it, you can't stop me from getting it - I WILL find a way to steal it from you. The biggest deterrent to theft is not letting me know you have it.
 
These guys laughed at alarms, locks, fences, dogs, etc. and had ways of dealing with all of them.

Jazzyvee , Thanks for posting this . I like it . I have played more bar gigs then I can remember  over the years . Some of the places had some  individuals there who had problems  with boundary issues. Many of us here have been and there and done that .  I think this would be a good deterrent  to keep your instrument out of such hands .
 
At large outside festivals with many thousands of people where a person can disappear in the crowd in seconds this might give you peace of mind. I just returned from  The SXSW  festival ,in Austin Texas , a huge wonderful loving bunch of folks there but all it takes is one Bad Apple  to get your Axe messed with and that's no fun .
 
I just might purchase this  Gizmo.  
 
 Wolf

The last time I looked into this item they weren't made for Basses? Anything change?  
Pete

That's an interesting insight David and yes it's a reminder that there is only so much anyone can do to protect the things they want to keep.  
 
At the moment I always carry my guitar/bass with me all the time when I'm not on stage unless someone in the band is staying backstage. Most of the gigs I play at there are a number of other bands backstage too and rarely any of the dressing rooms are locked so I would not consider the back stage area secure.  So being able to lock things down might well be enough to deter a casual opportunist but not a determined pro as In Bill's case.  
 
Pete I've not found anything that says it will fit bass but at $50.00 is not that expensive relatively so if I can find one this side of the pond and it fits my guitars that will be good and if it fits my bass also, then even better.
 
 Now if the cable could somehow be threaded through to the inside of my lockable guitar case and then locked into place that would be better than leaving a guitar unattended on a stand back stage.

On the other hand, you could use 'em to lock up the instruments of people whose music you don't like. I wouldn't be surprised if somebody does that to me someday.
 
Come back from break; oh man, somebody locked my bass to a stand! Oh no, they locked it on the fourth fret! Hey, do guys mind playing in A-flat for the rest of the night while I squat behind this stand and pound my bass's strings with a beer bottle? It'll be fine.
 

Does it double as a capo?
 
Bill. tgo

I never let my basses out of my sight at a gig, so I wouldn't have any use for it.

Bill, i'm sure Victor Wooten could do great musical things with it in Capo mode. I'm like you Rusty for about 99% of the time. But there are times that I'd like to leave mine back stage whilst I go watch the next band or just take in the vibe of the club, venue without carrying my bass. Or be totally relaxed about leaving it in my hotel room which is another area things can disappear. So far may current methodology has been fine but sometimes a little help is not a bad thing.

I would be concerned on the possibility of someone trying to mess with the cable lock, not being successful and then damaging the instrument, just for frustration, for the sake of it. My approach is the same as Jazzy's, try hard never to leave your instrument alone...

One more reason I'm glad I'm through playing out:  If I've got a real need for this, what the hell am I doing?  I don't know, it just makes me slightly sad.  
 
On the other hand, though, I can just hear Mr. . . . but these go to Eleven explaining to the cop that he had it locked to the 10-dollar guitar stand, and can't believe they took it, too . . . . .
 
Joey