I really like using iChat for IM but one thing that is a minor annoyance is having to click the “Accept” button when you receive a text invitation from an AIM account.  My preferred solution is to use Chax which offers a lot of other functions including chat logging.  However if you don’t want any of that stuff, in Snow Leopard you can configure iChat to auto-accept text invitations in the preferences.  On the “Alerts” tab of the Preferences, select the Event “Text Invitation,” check the box to run an AppleScript and select “Auto Accept” like so:

ichat-aut-accept