GPG is quite nice. I’ve only come to really appreciate it more recently with my delvation into Keybase.io and all the small, unimportant messages i can send to my friends:)
Here are some examples of using symmetric enc on single files.
Encrypting a file using AES256:
gpg --pgp7 --cipher-algo AES256 -c wallet.dat
Use/Load an encrypted private key in ssh-agent for 12 hours (without leaving an unencrypted copy on the fs):
ssh-add -t 12h =(gpg -d $HOME/.ssh/id_rsa.gpg) &> /dev/null
Of course, the best part about gpg is the public/private keys you can use to send messages/files to certain people and sign data for further assurances.
To get going with this sort of thing,