Psalms 66 is all about giving thanks to God. The psalmist is singing praises to the Lord and thanking Him for all the many wonderful things He has done. He talks about how awesome God is and how He is the only one who can save us. He also talks about how God has saved him in times of trouble and kept him safe. He gives thanks to God for His wonderful works and praises Him for His goodness. All in all, it's a pretty sappy chapter, but hey, at least it rhymes.