Security concerns are at the back of peoples minds when using the Internet. This is a bit of a worry really.
One thing that I used to do, which is probably the biggest security mistake you can make. Is use the same password on different sites. I know it is really difficult to remember many 10's of passwords, but you don't have to remember anymore then one password.
I use a password database application called Keepass (v1.18), it works across all the platforms I use. Linux (Ubuntu 10.04 & 12.04, Mint 12), Windows XP, Windows 7 and Android 2.3.4. Keepass is an encrypted database, I use both the master password and the key file options. Newer versions also have more options that I will look into soon, I will test these on all the platforms before I make the switch.
Now as you can probably guess from looking at the list of OS's that I use, there are a few computers that I use on a regular basis. To keep all these computers synchronised with the most up to date password database. I use Dropbox, this also works on all the platforms that I use. If you haven't herd of Dropbox yet then check them out at dropbox.com you can connect as many computers to your cloud storage as you want, I currently have 7 connected.
Now because Dropbox is a remote storage for your files, if you want to store sensitive files then I would highly recommend encryption. I use truecrypt, it is a bit of a learning curve, but it is free open source software and will ensure that your files are uncrackable. Hint use keepass to generate passwords for the truecrypt containers.
One final note, make your keepass master password a sentence, these are easy to remember and hard to break.
e.g. "MyPasswordIs: the quick brown fox jumped over the lazy dog" as a master password would be extremely hard to break. Basically impossible with current tech.