From what I've heard, God wants us to glorify him and give him praise, and he enjoys when we do this. Does God need us to do this for some reason?
There is a sense in which an attribute which is an action is not fully realized until it is enacted. Love isn't real without an object of affection. Forgiveness is ethereal until somebody has crossed you. Being a redeemer requires something to save.
I would not go so far as to say there was an incompleteness in God that he needed to fill ... that he had a NEED of recognition, but in there is a sense in which his had to have creatures to reveal himself to in order for all the fullness of his being to be legitimized. His Glory is glorified as it is beheld, even if it is beyond the grasp of the beholder.
I believe God is a full-on egoist in that his is fully self centered. Whatever he does he does for himself, and he expects/demands the same of others. Egoist can also have another connotation of being conceited and limited to caring about ones-self. I am not reffering to this. Being omnipotent it's impossible for God to have a delusional or exaggerated sense of self worth. If you leave out the definition of of megalomania that includes being delusional, I think it is safe to say that God is a megalomaniac in so-far as he is obsessed with his own power and importance.
Isaiah 48:11 (ESV)
For my own sake, for my own sake, I do it,
for how should my name1 be profaned?
My glory I will not give to another.
He desires and will have all glory for himself. Satan tried to reach out and take this from Him, and was cast out of heaven. Man was deceived and wanted to be like God in a way that was not his place to be.
For a man, or any other being, to be an egoist is sin. All created things were made by, for and in Christ.
Colossians 1:15-20 (ESV)
15 He is the image of the invisible God, the firstborn of all creation. 16 For by him all things were created, in heaven and on earth, visible and invisible, whether thrones or dominions or rulers or authorities—all things were created through him and for him. 17 And he is before all things, and in him all things hold together. 18 And he is the head of the body, the church. He is the beginning, the firstborn from the dead, that in everything he might be preeminent. 19 For in him all the fullness of God was pleased to dwell, 20 and through him to reconcile to himself all things, whether on earth or in heaven, making peace by the blood of his cross.
For any of those created things to focus on themselves rather than on the one-preeminent-being is sin. Being ego-centric is rightly considered to be a bad attribute when applied to a human, but not when speaking of God.
Being ego-centric is OK when you are The I Am. It is right for us to praise Him and serves a purpose of putting his Glory on display.
The Westminster Shorter Catechism states that "Man's chief end is to glorify God, and to enjoy him for ever." If that question had been about the chief end of God I would say it would read "God's chief end is to glorify Himself, and to enjoy himself for ever."
Does God need us to give him glory? No. That would also imply he needs us.
God wants us to give him glory because he is the only worthy one.
Pslam 96:4-6 (NIV) says
For great is the LORD and most worthy of praise; he is to be feared above all gods. For all the gods of the nations are idols, but the LORD made the heavens. Splendor and majesty are before him; strength and glory are in his sanctuary.
When we put other people/things before God, we sin because those are idols. God hates sin. God wants whats best for us so by wanting us to glorify him, he is wanting us to turn from our idols.
God does not need our praise as He is self-sufficient.
But I want to add another glitch to the discussion: We do need to glorify and honor Him.
Who do you believe the most? Yourself. So if you hear and see yourself glorifying and uplifting God, it helps changing your conception of God: He in your eyes becomes even more worthy of praise. This keeps you in a close relationship with Him and gives you the power to follow through.
So in His command God mostly thought about us, not Himself. What a great God.
God lacks and needs nothing. God has been perfectly satisfied and joyful in his own nature from all eternity. God is perfect, and God needing something implies insufficiency and imperfection.
That being said, God might be obligated (to himself) to express his glory fully, and, in a certain sense, that requires spectators. If a tree falls in a forest and there is no one to hear, does it make a sound? What would it mean if God expressed his glory with the greatest symphony or the greatest universe, if there was no-one to see it but him? In the same way, glory is not full, in some sense, without someone else to see and enjoy it.
(No, perhaps God is the only spectator that matters. Still, it does seem a logical step for an infinitely great God to express his glory to creatures.)
Once God creates people, they would be obligated to acknowledge this glory, and to do so often and with joy (as is fitting and honest). And God, if he was good, would make himself known to them, as he is the highest and only good that exists.
Along the lines of what Caleb said, for a man to be self-centered is an evil, because it robs God (the only one who actually deserves worship) of worship. But for God to promote himself is a virtue, because he is ultimately what is best for people.
He is best for people because he is infinitely glorious, because nothing else has any value besides him, and because whatever has value has value only because of him. It is the ultimate good to be united to the infinitely glorious God. For God not to promote his own interests would be the cruelest crime of all!