The thieves on the cross are an excellent demonstration about the choice we are all faced with - who do we believe Jesus to be? Do we believe He is who He claims to be? And if we do, will we follow Him as Lord and Saviour?
This passage also gives us the certainty that immediately upon our physical death, those that follow Jesus will be with Him forever. What hope!
I also love the portion of the passage that describes the temple curtain being torn in two. This curtain separated the people from the presence of Jesus, but Jesus' sacrificial death removed that barrier, and we can now have access to God. This is something that is so "normal" for those of us that grew up in the church, but I can't even imagine how amazing it would've been to the Jews in Jesus' time!
Tomorrow's Bible In a Year Passage: 1 Samuel 30-31, Luke 24