You'd be amazed at what thieves will steal off a bike. Protect your saddle with Avenir's Seat Locker. This simple, lightweight cable secures your seat to your frame with any style padlock.
Sunlite's Erector Link Lock folds down into an easily portable package. It's made from steel so it's tough to cut, and includes a drawstring carrying bag. This is a key lock that is 2.6 feet long.