For roleplays that require a lot of lore, I use Google Docs and add a visible link to it. You can make it easy to navigate with the outline or table of contents, you can edit in real time with collaborators, you can let RPers make additions that you have to approve first, and you can make out of bound comments on various articles.

It can also be used for your GMs/Co-GMs planning sheet.

Damn, I sound like a Google sales representative or something.