AT FIRST GLANCE, the Web site SeekingArrangement.com seems like any other dating site. Most of the men are looking for fit, sexy women, and most of the women want nice guys who can make them smile and laugh. But if eHarmony or Match.com is a chatty social mixer, Seeking Arrangement is a down-and-dirty marketplace where older moneyed men and cute young women engage in brutally frank transactions. They're not searching for longtime soul mates; they want no-strings-attached "arrangements" that trade in society's most valued currencies: wealth, youth and beauty. In the cheesy lexicon of the site, they are "sugar daddies" and "sugar babies."