[JeffF.]

I agree, the ring drew the orcs that wiped out Isildur's guard when he lost the ring near Gladden Fields, it drew the Watcher in the Water to Frodo out of the whole group and the orc chietain in Balin's tomb bypassed both Aragorn and Boromir to thrust at Frodo. I also think the Balrog was drawn out of hiding toward the power of the ring. To an evil force such as the Balrog it must have seemed irresistable.

Still, given Sauron's rank among Morgoth's minions as his second in command I think there was some possibility of him drawing the Balrog into his service. in Unfinished Tales Gandalf mentions that Sauron could have made great use of Smaug had Gandalf not contrived to have him slain and it seems to me Smaug and the Balrog were probably similar in power and evil.