If it's serendipity that you're looking for, Craigslist can't be beat. Anyone can post a personals ad for free to this virtual classifieds site, which is why the ads can run R-rated (the site now posts a disclaimer before users can read the ads). But there is literally something for everyone here, no matter what your orientation or their intention. Bookmark the site's missed connections page for a good laugh — and in case Mr. or Ms. Right also noticed you on the subway this morning.