[eluser]bigtony[/eluser]
Take a look at the [url="http://ellislab.com/codeigniter/user-guide/helpers/cookie_helper.html"]Cookie Helper[/url]
What you could do is store a cookie on the user's browser when they login. Then in future your site can try to load the cookie, and if exists with correct value you can do an auto-login. You'll need to set the cookie to exists for a while, say a few days or whatever makes sense to you.
