I mean, types of pages? Here are the ones I've noticed.
Regular pages include articles, talk pages, and user pages.
Here are the non-regular pages I've noticed:
Blocked IP's Recent Changes Watch List User Preferences Page History (now called Older Versions) Related Changes What Links Here (and maybe Where This Links To)
Which ones did I miss? I'm doing this enumeration so I can look at the database schema and see what information is actually needed, and what isn't, and what would allow for optimal access and use of space.
For instance, right now, the "options" field could be a simple integer index which refers to a specific CSS file; when a user changes their options they would get linked to a different CSS file, that is all. I don't know, maybe that is already what happens.
Jonathan