Okay, so basically I've been at this for 3 days. I've set up all the things for my server, including forwarding a port and I can connect to it just fine with the external URL. But my friends aren't able to connect to it. I tried turning my firewall off, my antivirus off, and even tried setting it up on a different computer. Here's all the details:
#Minecraft server properties
#Sat Sep 25 17:00:38 EDT 2010
motd=Welcome to my Minecraft Server\!
Any help would be greatly appreciated! I'm losing my mind.
Make sure that underneath "server-ip=" you have nothing after it. You do this because people will be trying to connect to your external ip which is dynamic, so it can change. The minecraft server will automatically detect your ip this way. Second, make sure your friends are trying to connect with your external ip. NOT the one that is "192.168.x.x. To find your external ip, just go to this site: http://www.whatismyip.com/ and it is located at the top.
Second: Make sure you have opened the port 25565 (or whatever is specified in the server properties) on your router. If it's closed, no one can get through. And don't listen to what ever the Port Checker by PortForward.com says. I opened the port and have a running server which external players can connect to, but the Port Checker says my port is not open. it isn't accurate.