In Dragon Magazine #319 page 73, in a sidebar, I found an exotic weapon that is basically a spiked chain mixed with a whip. The meteor hammer/rope dart has 15ft reach like the whip, but there is no clause stating that the weapon does not threaten the squares that it can attack in, unlike the whip. So in trade for reduced damage (1d4), you can put an extra 5ft on any spiked chain build. (Plus, it is 20ft of rope in a pinch) It allows tripping, gives a +2 to disarming, is finessable, and you can even use it as a monk weapon if you take the proficiency feat for it.
The only real downsides are the halved damage and the fact that it comes from a Dragon Magazine.