While RTFM is always a good idea, I can sympathize with your question because module names and descriptions can be quite confusing.
Here are some hints:
mod_alias - Keep it.
mod_auth - Simple HTTP authentication (pops up a username/dialog box in browsers). Most PHP apps do not use this, so its probably safe to disable.
mod_cgi - Do you use CGI scripts? Perl scripts? Lots of form mail scripts are CGI scripts, but if you're a PHP fan, probably not. Disable it.
mod_dir - Keep it.
mod_mime - Keep it! Its needed for PHP's handler directive.
mod_mime_magic - Basically a backup for mod_mime. Probably not required on a well configured system, but
keep it just to sleep well at night.
mod_negotiation - You probably don't use it, but you might want to keep it. Apache itself uses it for the default document root files.
mod_rewrite - rewrites URLs, used by some apps, such as Drupal, to create "pretty" or "clean" URLs. if none of your Apache conf files or .htaccess files contain a "Rewrite" statement, you might as well remove it
mod_ssl - If you don't use SSL (https://), you might as well disable it
mod_status - If you're asking about this one, then you don't use it.

Disable it. You can play around with it if you want, its kinda neat.
Alright, that should get you started at least. Check the page komy suggested for rest.