How to denote a user as a "system account"? In the Unix world, there are "user accounts" for humans to use, and there are "system accounts" for software to use.

On a Drupal site, I have a couple of system accounts intended for use by services.module API calls.

I'd like these accounts to be able to log in via the services API (obviously), but I would like to block these accounts from being used to log in via the standard user_login form.  I'd also like to prevent these accounts from showing up in standard "active user" lists, such as the "Who's online" block.

How should I approach this?
Have you had a look at using the API key authentication? This will enable you to login effectively without using a username + password combo.

See http://drupal.org/node/762092 for more information