I wrote it because I wanted something more secure than what is currently available. It is described in detail on this page. You can access it from your browser from this link.
Here is a screenshot of PassMan using example data.
Although you can use the tool directly from this website, the source code is freely available under the terms of the MIT license and can be downloaded from http://projects.joelinoff.com/passman/passman-v0.7.tar.bz2. It is about 4MB. The version is 0.7, the check sum is 45452 and the number of blocks is 4138. The check sum was generated using the linux sum command.
There is a password generator named PassGen available. You can use it to generate long, pseudo-random passwords.
There is another a password generator named PassGenW available. You can use it to generate long, pseudo-random passwords that are composed of English words.