The word "bless" shows up in some sort of form in 65 verses in the book of Genesis.  As I listened to the book this week, it seemed like everyone was getting blessed all over the place.  Here's the list of who blessed who:

• God blesses the creatures He created
• God blesses Adam and Eve
• God blesses the seventh day
• God blesses Noah
• God blesses Abram (a bunch of times)
• God blesses those who bless Abram
• God blesses the world through Abram
• Melchizedek blessed Abram
• God blesses Sarai
• God blesses Ishmael
• Laban and Bethuel blessed Rebekah
• God blesses Isaac (a bunch of times)
• Isaac blesses Jacob (oops!)
• Isaac blesses Esau (thanks a lot...)
• God blesses Laban (he learned this by divination)
• Laban blesses his grandchildren and daughters
• The angel Jacob wrestled with blesses Jacob
• God blesses Jacob (a bunch of times)
• God blesses Potiphar's household because of Joseph
• Jacob blesses Pharaoh
• Jacob blesses Ephraim and Manasseh (backwards!)
• Jacob blesses his sons

Obviously, there is something more going on here than a lot of sneezing.  (See the origins of "God bless you" here.)  What is the importance of this blessing?  Well, I'm looking forward to a comment from Mike R on this, who is my resident OT expert, but I'll give it a shot.

First, one thing that all these blessings point out is that God is the one granting favor and gifts and talents and treasures.  If anyone, like Abraham, Isaac, Jacob, Moses, Noah, receive any merit, it is because it is granted to them by God.  It is the same with us.

Second, it's a preparation for Christ.  Let's let Packer take the floor:

God’s covenant with Israel was preparation for the coming of God himself, in the person of his Son, to fulfill all his promises and to give substance to the shadows cast by the types (Isa. 40:10; Mal. 3:1; John 1:14; Heb. 7–10). Jesus Christ, the mediator of the new covenant, offered himself as the true and final sacrifice for sin. He obeyed the law perfectly, and as the second representative head of the human race he became the inheritor of all the covenant blessings of pardon, peace, and fellowship with God in his renewed creation, which blessings he now bestows upon believers. The typical and temporary arrangements for imparting those blessings were done away with through the realizing of that which they anticipated. Christ’s sending of the Spirit from the throne of his glory seals God’s people as his, even as he gives himself to them (Eph. 1:13-14; 2 Cor. 1:22).  

Packer, J. I. (1995, c1993). Concise theology : A guide to historic Christian beliefs. Wheaton, Ill.: Tyndale House.

We are blessed.  If you don't feel blessed, read God's blessing on you in the book of John.  It's one huge blessing from God, rescuing us from ourselves, just as He did in Genesis.

Cool.