DO NOT USE THE SAME PASSWORD IN MULTIPLE PLACES!!
Once your password is compromised in one place, people can attempt to use it all over the place. I'll keep it simple. On a lot of websites, the administrators have access to your password. Now, imagine that there's an evil administrator, or that one of the sites you go to was hacked. And, there are also websites out there that specialize in linking your real name to your online aliases. You've been here since 2001; I think that the majority of members who have been here that long can be tracked down to an address and real name.
Now, having your password, let's say here, I can *automatically* attempt your name here (Muse), or your real name all over the internet - 1000's upon 1000's of sites looking for other accounts, etc. That's why it's a really big deal when someone hacks some corporate website and obtains a list of users and their passwords. It's not because the hackers are going to do more at that website - it's because the hackers are going to scour sites like bank of america to see if you have an account with you name and the same password.
One thing you can do is use *almost* the same password everywhere.
facebook's password would be gpassword
yahoo's password would be zpassword
gmail's password would be hpassword
anandech's password would be bpassword
Can you spot what I did? I took the first letter of each site and went up one letter sequentially and tacked it on to the beginning of password. If someone got your gmail password of hpassword, they're going to hope that hpassword works for accounts in your name elsewhere.