Here are some sites I've used for information, as well as links to other peoples fan projects, or just more Metal Gear stuff in general.

Metal Gear Wiki

I know, I know, fandom wikis kinda suck to navigate nowadays (especially if you don't have an adblocker!) but theres a lot of easy to find info on just about anything, and the site's very helpful for making my own pages for the site.

The Snake Soup

One of the oldest Hideo Kojima fansites created in 2003. Has a lot of neat pages including 'Myth Articles' which debunks common misconceptions among the Metal Gear community. I am warning you, though, the oldest one of these articles is a bit childish.

ThorHighHeels's Metal Gear Solid retrospective

A series of Youtube videos that look back on every single entry of the Metal Gear series. Some of you Kojima fanboys might get pissed at some jokes, but I think they're funny.

Shadow Moses Cafe

An MGS lore podcast that goes very in-depth with its character analysis. They even did an episode with Christopher Randolph, the voice actor for Otacon and Huey!

Podcasts Sans Frontieres

Another mostly lore-focused podcast. I haven't listened to all the episodes but from the ones I have listened to they're really good!