Yea, I've met some cuties online before. Match.com is probably the best site for decent looking girls. Some are complete sluts looking for a free drink and a hookup. Others are nice girls frustrated with the bar scene and are trying something different. I met more of the latter than the former and have had (edit) one decent relationship from there.
For Washington DC and New York City, you find a lot of mainstream women and men trying it because they're tired of the bar scene. Lots of students, single professionals, lots of people in their 20s and 30s. Basically the majority that I've seen are those that focused on their career first but are now wanting to slow that down and find some cool people to hang out with. Sometimes it works, sometimes it doesn't. I tried it for a change of pace and to try something new. Not ashamed of it at all. At first I was nervous of the stereotype but when I saw how many people I know were doing it I lost all hesitation about it.
I think the key is being honest with who you are from the get go and looking for someone who will be that way to you.