I recently wrote about some passages in the gospels that support the doctrine of justification through faith alone. When I discuss the subject, I often cite some of the same few passages each time, like Mark 2:5, Luke 7:50, and Luke 18:10-14. However, the concept is found in a lot of other passages in the gospels as well.
In the Synoptics, some of the healing passages suggest that salvation, not just healing, has occurred through faith (Matthew 9:22, Mark 5:34, 10:52, Luke 8:48, 17:19, 18:42). For example, Jesus sometimes tells these people to go in peace, which would be unlikely to occur if something less than justification had occurred. (For a discussion of why such passages should be seen as references to salvation, not just healing, see, for example, Darrell Bock's comments on the Lukan passages in his commentary on Luke in the Baker Exegetical Commentary On The New Testament series.) In Luke 19:1-10, Zaccheus receives salvation in a context that doesn't mention baptism and in which baptism would be unlikely to have occurred. The gospel of John often refers to the concept of receiving eternal life through faith (3:15-18, 5:24, 6:35, 7:38, 11:25-26, 12:36, 20:31, etc.).
People often object to justification through faith alone on the basis that those who advocate the doctrine only find it in the writings of Paul. It would still be a Biblical concept if it was found only in Paul (and the other apostles agreed with Paul, as we see in Acts 15 and 2 Peter 3, for example), but it's found in many other portions of scripture as well.
It should also be noted that this doctrine is a particularly significant example of the unity of the apostles. While the religions of the world commonly teach some form of salvation through works, Christianity began with a message of justification through faith alone, repeated often and not just in the writings of Paul.