I found this interesting site that can determine how much money to give to a couple for their wedding. I was very surprised at how much it says I should give. I went to a wedding this weekend and I plugged in the info it required. I gave the couple $200 but the calculator said I should have given them $350. It didn't take into account the fact that the bride is a partner in a corporate law firm and her DH is a corporate accountant and they bring in at least 10 times as much as we do. But, I still think it could be useful.
http://www.theweddingenvelope.com/calculator.php