LambdaPlusJS (or LambdaChan) [I2P] // Imageboard only accessible through alternative networks. No use of Javascript and no censorship (far as I've seen).
Misc/
treasure_chest [I2P] // File server containing plenty of cool stuff, such as uncle Ted's writtings. HTTP access is read-only, but you can write and modify files if accessing through SFTP or CIFS.
identiguy [I2P] // Basically how you can find interesting eepsites most easily. Read the disclaimer before anything.