A massive photographic archive of the US Navy.
The USS Pennsylvania Web
A website about battleship USS Pennsylvania (BB-38), the sister ship of the tragically famous Arizona (BB-39).
Battleship Texas
A very well documented website about battleship Texas (BB-35), the only surviving one of her kind.
The Imperial Japanese Navy Page (Nihon Kaigun)
A nice website about the IJN.
A website showcasing various military uniforms, mostly British, throughout history.

Other things

Bonnibel's Graphic Collection
A massive collection of graphics that you can put on your website.
A very varied collection of .txt files.
Last Words
The last words of pilots before plane crashes. Air traffic control tapes, cockpit recordings, and transcripts. Caution: may be disturbing.
The Geocities Gallery
A collection of archived Geocities sites. A nice rabbit hole to go down.
The Surrealist
A bunch of fun and weird random text generators.