Reverse ICMP Shell - https://github.com/commonexploits/icmpsh
One-liners - http://bernardodamele.blogspot.com/2011/09/reverse-shells-one-liners.html
Upgrading to TTY - https://blog.ropnop.com/upgrading-simple-shells-to-fully-interactive-ttys/
Cheatsheet - http://pentestmonkey.net/cheat-sheet/shells/reverse-shell-cheat-sheet
Netcat