*update* Truecrypt now has its own GUI, see here, This post remains for archive purposes.
I have always been security conscious, in todays world privacy & security is a thing of the past unless we take matters into our own hands. I have used many types of encryption applications, dm-crypt, luks, cryptsetup, encfs, and truecrypt. personally I like truecrypt more than all the others simply because you can hide encrypted files in encrypted files. This is a form of steganography and is a better deterrant to law enforcement than full disk encryption, with that judges and juries seem to think you are indeed hiding something and you should be punished. I found this powefull little applet for gnome that complements truecrypt very nicely. I can simply right click & and create & mount truecrypt volumes.
This is all you do:
sudo apt-get install python-crack python-pexpect cracklib2
tar xfz truecrypt-4.3a-ubuntu-7.04-x86.tar.gz
sudo dpkg -i truecrypt-4.3a/truecrypt_4.3a-0_i386.deb
rm -rf truecrypt-4.3a truecrypt-4.3a-ubuntu-7.04-x86.tar.gz
sudo dpkg -i forcefield_current_all.deb