Omegle - A fast riser
Omegle.com is one of those site that appears out of nowhere, catches people the right way and rises instantly. It has also been able to sustain traffic over 2 weeks because it keeps getting mentioned as new people discover it. Look at the Alexa rank:
Alexa stats for Omegle
Here's a typical blog post - the kind that has given this site traffic over the last two weeks:
xkcd on Omegle
Omegle has a Good, short, unique name that is easy to remember. It has a simple concept that is easy to explain. It has simple, clean execution on its idea.