The best replacement for pgp is gpg.

The best alternatives to pgp are rated as following:
★★★★★  gpg
★★★★  truecrypt
★★★  s mime
★★  ssl
★★  pki
★★  sciatica
★★  aes
★★  rsa
★★  bitlocker
★  sftp
★  smime
★  gnupg
★  spd
★  md5
★  s/mime
★  pgdm
★  ssh
★  tls
★  x509
  pem
  aes-256
  pretty good privacy
  rainbird 5000
  pgp ultra
  otr
  efs
  i-20
  pointsec
  xpadder
  rsa pki
  secure ftp
  s\/mime
  openssl
  x.509
  kerberos
  winzip
  openpgp
  drivecrypt

Your alternative for pgp is not listed? Suggest!
Speaking about pgp, one probably shouldn't forget about sftp.

Other search terms related to pgp and their ratings are:
★★★★★ sftp
★★★ ftp
★★ webmail
★★ tormail
You have in mind a companion for pgp and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of pgp in all years. Click on graph for more.
pgp
gpg
truecrypt