It's amazing how many websites completely drop the ball on security. There are some pretty trivial security measures that just can't be overlooked. Among the most important are SSL and password hashing.
SSL is the technology that, when used, encrypts the data sent to/from your computer to a remote computer. The best example of this is when you type your login credentials into a website. Your browser sends your username and password to whatever website you're logging into. Without SSL this information is transmitted in plain text, and can be intercepted and sold/reused/etc.
Password hashing is a technique of storing data...