Account Lockouts

Hello all, 

My question to the group is about handling account lock outs.  Here's
the situation, assume there is a web interface that lets users log in
and do stuff, but the log-in process is constrained by the network
restrictions as well.. Meaning if a user tries to log in X times in Y
seconds and fails each time, then the account get locked out.

What are successfull techniques that could be used on the web
interface to avoid having a script run against it that would
potentially lock out 15000 user accounts, and create a headache for
the system administrators who have to manually unlock each account?

Also assume the current user account names are known by everyone.  

Possible techniques we've thrown around:
1)  Allow each user to pick their own username instead of using a
standard (i.e. First 3 letters of first name + Full last name)

2) Create a set time-out period  for each account of  X (maybe an hour) 


Hopefully my question makes sense.  

Thanks,
Harrison
-- 
___________________________________
Harrison Gladden <hgladden@gmail.com>
Computer Engineer & Science Major
~Past experience: He who never makes 
   mistakes, never did anything that's worth.~