For those were talking about the hassle of having to re-enter your username and password each session, there is an option in most internet browsers that can be set to store your login details.
However for security reasons you should only ever use this on your own computer - not one that is shared by anyone else.
In Internet Explorer 7 this option is under Tools > Internet Options > Content. Go to the Auto complete section. Click Settings and check the box 'usernames and passwords on forms'
Next time you go back in to the forum and you start typing your username it should populate with the login details you previously entered (which hopefully you typed in correctly!)
In Firefox there's an option to Remember passwords for sites under Tools > Security.
But please remember you should only do this if you don't share a computer - otherwise someone else can access a site as if they were you.