You can use exploits or cracking software to aquire a username and password, or just the password if you already know the username. wwwhack is one of those tools and so is BrutusAE2. checkout www.hoobie.net or www.elhacker.net. Astalavista!
Or, if you know the hash of the password you can submit the hash to http://www.milw0rm.com and they can crack it for you, there is also a tool called "cain & abel" you can submit hashes through "Cain & Abel" to rainbowcrack-online.com which is a SSL enabled site to ensure that your hash doesn't get sniffed out...
