Unless you're named Joe Smith or Jane Jones, most of us leave traces online. Google can usually turn up a few details: where someone went to school, how fast they ran that marathon, the comment they left on that bulletin board. It's fine to search but don't mention it to your prospective datee. There's a fine line between cyber-curious and cyber-stalking.
And be careful what you divulge about yourself over email. It's OK to be vague about your employer, home address, telephone number until you get a real sense that you can trust someone.