The letter from Jude is the last of the epistles to the early churches. Jude calls himself the brother of James, so we can assume he's also the brother (or half-brother, technically) of Jesus.
Anyway, Jude's letter is just a quick reminder not to follow false prophets, whom he earnestly explains as being evil. This letter is more important for understanding the history of the church than for understanding the teachings of Christianity, I would say.
And next Revelation, which is the final book in the New Testament, and, in fact, in the whole bible. I've been warned I'm in for a bumpy ride. Should be interesting...