i hate seeing email used as a backup file archive but i suppose the wallet.dat is such a small file that sending it encrypted through email is not going to consume too much space.

pgp itself is secure.  if you have your email client do stuff like "remember password" or something like that, then you might not have a secure wallet.

and don't forget the rule of thumb.   you don't have a backup until you've verified with testing that your backup can be restored.

You could use 7zip and put the file in a self extracting archive with 256bit encryption. Quick and easy. Rename the file, send it to your gmail let it hangout.

be very careful man,, buddy on here just reported losing 7208 fucking coins!

for backups that are being distributed en masse and stored long-term, you'd be well advised to use a modern cypher rather than 3des or cast-128. truecrypt gives you good options. at least pick aes256 manually if you're using gpg.

i wasn't suggesting public-key cryptography; gpg also handles symmetric cyphers. it may not make much difference in practice depending on your threat model, but 3des is strictly a poorer choice than aes256.