Usefull pages to often come back to.
ywstd.fr - "Ypnose's enclave"
Creator of wswsh, ahrf and other nice and useful stuff, who has been very helpful. Loves simple and suckless software. 
decentsecurity.com - "Start somewhere. Start here."
Entry level guides to security.
Pass by to get started or to keep up with the latest essentials.
Also has an enterprise level section. 
bolthole.com - "bolt-hole: a place of escape or refuge"
Collection of guides to get into programming and other stuff.
The tutorials for AWK and KSH helped me a lot. 
Frank helped me debugging my suggested installation of Prosody on Uberspace.
He blogs about Linux and OSS on Desktops, Servers and RPis and also other stuff.