Oi! - The Truth
This is the notorious Gary Bushell's history and defense of the Oi! Movement, written in 2001.

Flat Earth Records
Run by Sned who was in Generic and Electro Hippies (as well as several bands in the 90's and beyond), there's some flyers and photos from the 80's on this site.

Punk & Oi in the UK Website
Although much of the focus on this site is the current scene, in the interviews section you can find lots of info on 80's UK bands. (It might be a little hard to navigate, so here's a shortcut)