St. Jude Thaddeus
Ancient writers tell us that he preached the Gospel in Judea, Samaria, Idumaea, Syria, Mesopotamia, and Lybia. According to Eusebius, he returned to Jerusalem in the year 62, and assisted at the election of his brother, St. Simeon, as Bishop of Jerusalem.
He is an author of an epistle (letter) to the Churches of the East, particularly the Jewish converts, directed against the heresies of the Simonians, Nicolaites, and Gnostics. This Apostle is said to have suffered martyrdom in Armenia, which was then subject to Persia. The final conversion of the Armenian nation to Christianity did not take place until the third century of our era.
Jude was the one who asked Jesus at the Last Supper why He would not manifest Himself to the whole world after His resurrection. Little else is known of his life. Legend claims that he visited Beirut and Edessa; possibly martyred with St. Simon in Persia.
Jude is invoked in desperate situations because his New Testament letter stresses that the faithful should persevere in the environment of harsh, difficult circumstances, just as their forefathers had done before them. Therefore, he is the patron saint of desperate cases and his feast day is October 28. Saint Jude is not the same person as Judas Iscariot who betrayed Our Lord and despaired because of his great sin and lack of trust in God's mercy."
As far as I can tell, not much is known about St. Simon, and their is no popular devotion to him. St. Jude on the other hand, well, prayers, novenas, etc.