Depends on the scripts. If each is similar in its authentication methods, then yes. If not, then it'd be a bit more difficult, but still possible.

Basically, what you'd need to do is figure out which scripts need to be included from which package to do the authentication. For example, for SMF you'd have to include either SSI.php or the actual login.php files. For phpBB it'd be something else. Joomla and Drupal are different too. And that's just community and CMS packages, not to include shopping carts and photo galleries.

So it really depends.

None are near as complex or massive as those. They are all small scripts for example one is for posting job openings, one for live support, one for job progress for jobs in progress. It is on a website for a business that are implementing these features into their web content.

What do you think about just putting them all to share the same database then using the same user table in the sql, would that do it?

Sharing the same user table would definately and would be the preferred method.

one more question, say a user table for one script differs from the others, like for instance, one has

username - user ID - first name

and another has

username - gender - location

as the user table boxes to insert. Can I somehow just add spaces for all of the attributes for all the scripts in one user table and just make sure that on signup they provide info for all spaces, then the scripts can sort of pull the info they need? Heck, I'm confusing myself now, not sure how to word this one, hopefully my question makes some sense.