Either the Aaronic benediction of Numbers 6:24-26 or 2 Corinthians 13:14. God has the first word with the call to worship and he has the last word with the benediction. This reflects the dynamics of the covenant of grace.
Our services have the pastor giving the benediction from the Word, usually the priestly one. However, while in Mississippi recently, their tradition was to have a man in the congregation give the benediction in the form of a parting prayer, and to my surprise I was asked to do this for one of the services. I did so, though I had never done such in the past and I'll admit that I felt somewhat awkward.
The Pastor invites the congregation to stretch forth their hands and then he pronounces a scriptural benediction. God has the first and last word.
In most Presbyterian churches I believe only a Pastor can pronounce the benediction.
My favorite is Hebrews 13:20-21, Now may the God of peace who brought again from the dead our Lord Jesus, the great shepherd of the sheep, by the blood of the eternal covenant,equip you with everything good that you may do his will, working in us that which is pleasing in his sight, through Jesus Christ, to whom be glory forever and ever. Amen. (ESV)
The very last thing we do is scramble to put all of the chairs and equipment away. The second to last thing we do is stand in a circle, hold hands, and sing the first verse of "God Be With You 'Till We Meet Again".