There are literally thousands of dating web-sites. Personally - I would say stay well away from them - especially as you don't really know who's at the other end of the computer ! You're better off joining a youth-club or other organisation specifically designed for teens. That way, you'll meet real people of your own age-group, and can get to know each other in a safe environment.
Single parents can meet each other by going to various school activities. They can also meet on dating websites that are aimed mostly at single parents.
In Latin America many teens must introduce their friends to parent before going out with them
There are several dating websites available for Christian singles to meet such as Christian Mingle, Christian Dating, and Single Christian network. These are places where single Christians meet each other.
There is a Christian website where teens can meet and chat with other teens, make a profile, read devotionals and more. Follow the related link.
Go to the pool! Meet other teens.
You could meet them on other online dating sites for teens, or meet someone around school areas, or in a random place like a mall or something.
You can meet other Jewish singles on a variety of different websites. Examples of such websites are Jewishcafe.com, Jpeoplemeet.com, and jewgether.org.
Trevorspace.org is your best friend for that!
They haven't meet each other
You can arrange a meet between them. They can be comfortable with each other when they meet.
Russian women typically meet each other in similar fashions as American women. They meet is places such as coffee shops, restaurants and other drinking establishments.
As far as I can tell there are no websites. As a suggestion, you could meet people at the gym. The problem with websites is that people do lie so be careful.