We all have personal data that needs to be secure. Be it password files, financial data etc.
I use Truecrypt to encrypt my important data. It does not matter if it is on a hard drive or a memory key any other media. You create a Truecrypt volume or volumes of any size and it becomes a virtual encrypted drive. The product uses AES-256 encryption, is fully open source and best of all it is free. You can also use Truecrypt for whole-drive encryption. Using Truecrypt is easy, when you want to access the data you start up the UI, select the file, click mount and you will be prompted for the password.
I also have an encrypted volume on the memory key I have attached to my car keys. The file appears to be
a 1G file of random data but I would be comfortable handing it to someone knowing that with a strong encryption key the data is very secure.