I would say something in this order:
Just point out how pretty the brides maids are... *clap clap clap*
Why you were picked as best man, what you first thought. (You were the cheapest?)
When you first met Boring Bob
When you first met Boring Bob's wife, what you thought of her - say something ground breaking (not neccesarily true), like ...and when she did that I knew her and Boring Bob were meant to be. Egg it on a bit.
If you can, slip in a few jokes. I.e. Wouldn't even come to his own stag, surprised he made it to the wedding as you'd expect him to be mercilessly bringing western justice to Ahghanistan, taking on the Taliban....on his PS3, maybe mention that you had such a hard time, that you had to ask randoms for advice.
Offer some advice at this stage, i.e. marriage is all about give and take.....you give, she takes... about 5 things should be enough. Can be found on the net if you're struggling.
Pour on praise to the wife, how she's the best thing that's clearly happened to him - anything that gets a guy away from a PS3 is a result - how lucky he is to have her.
It's been a pleasure and an honour to be a part of this great moment and raise your glasses to the bride and groom....