Where would you try to advertise an information resource provider for small businesses? I am not selling anything but want to find good advertising opportunities for the information that I am providing (business management, marketing, etc.).

Well first of all, adding a link in your signature when posting on forums like this is a good place to start. If you want to spend money on advertising, I would suggest AdWords or Overture.

Generally try to find websites/directories/forums with content closely related to your own. Check if they are willing to list your site. This will provide you with free traffic from the search engines, provided that you use this strategy wisely.