You want the password for a webserver:

-Brute Force:
Guess a Billion times by using a program or by teetering away yourself

-Social Engineering:
If you can convince the ISP or Host that you are the host of the site, they might be able to help you in someway...

-Keylogger:
Put a keylogger on the users machine and have the logs sent to you

-Watch those packets:
Get to the head of his/her network and set up a program that catches all the packets (ethereal, windump, tcpdump) however this may not work if they SSH or use any secure login.

-Ask the person:
Pretend you are someone you are not and ask the webmaster for his info. Maybe you are his DNS server host and you are working for tech support

-Find an exploit of some sort:
Then you don't need a password

Regardless if you have good intentions or not, this is an information site that provides information. If you were to ask a college professor this same question in class, I am sure that they would answer it instead of giving you a lecture about "That's not where you need to stick your nose"