Psalm 6 - David is known as a man who grieves over his own sin. He cries to God for mercy but he still feels the remorse of having sinned against God. He knows the workers of iniquity will always try to drag him down into their sinful lifestyle.
Psalm 8 - This is one of the greatest passages in the Bible that shows the majesty and glory of God! David wonders how God could even give man a "glancing notice" when he sees all that God has made. But yet he marvels at what God has called men to do in His creation. God has a Name that is excellent in all the earth!
Psalm 9 - David rejoices over God's victory over David's enemies. Other people are caused to see God as their refuge and the One they can trust. It's in this psalm where David says that nations that turn against God will be "turned into hell."
Psalm 10 - David gives a description of wicked people in their luxury, their pride, their schemes, and their arrogance against God. However, the Lord is fully aware of these things and He will bring justice. God is King and the nations of the wicked will perish.
Psalm 14 - This and Psalm 53 are almost identical. This could be called "The Atheist Psalm" because it starts off by saying that anyone who denies the existence of God is a fool. You will also see the background to the passage in Romans 3:10-12.
Psalm 16 - This is one of the great Messianic Psalms that speaks of Christ especially that His body would not see corruption in the grave. This was quoted by Peter on the Day of Pentecost. This also reminds believers of what they have to look forward to in heaven where they will enjoy "pleasures forevermore."
Psalm 19 - This psalm describes the power of both creation and the Word of God to declare God's greatness and speak to the heart of man. Hidden sins need to be confessed and the words of our mouths and the meditations of our hearts are our responsibility.
Psalm 21 - David writes of God's blessing on the king in many different ways, but a special note is made in verse 6 of the gladness the king has in the presence of God! God is the One, however, who will ultimately be exalted.