Sanackranib said:can the Spiked Chain be used as a double weapon?
not so much as written because it doesn't state anywhere that it Is a double weapon (all the double weapons are describer as such.)
However, you could rule that it could be used as a double weapon that does a d4/d4

Also Spiked Chain is a heck of a weapon, if you dedicate the character to it.
Using a reach weapon and a 'standard' melee weapon requires more feat usage to max out both weapons potential.
It would take twice as many feats to weapon focus and specialize two weapons. Also cost twice as much to "magic up" both of them.
Feats to take as a spiked chain fighter to rock are:
Combat Reflexes to provoke those tasty AoO's "Come into my Zone OF Terror!"
Improved Trip!.."Trip..Smack! Doh!"