Really? I've heard of people lying about their age (children say they're 18, 30+ adults say they're twentysomething, and pedophiles say they're children), their appearance (black hair instead of gray, or maybe a bit thinner than they really are), their income (always richer than they really are), their email address (Actually, this is the only thing I've lied about: I always munge mine to stop spam.), and even the standard spam scams: $6 scam, 419 scam, and phishing. Never heard anyone lie about race, save for a few New Age wannabe-Indian types (and even then, that's just a whole con to make money, so it can be classed with spam), though I guess it would just be an extension of lying about appearance.
IM and chatrooms are where most of these lies occur: Let's just say the flame in AIM stays mainly on the insane.