1st of all, to check if your email was in the recent Yahoo leak, check out this website (it doesn't have to be a Yahoo account, don't ask me how :s but one of my gmail accounts was compromised), I landed on that website from TechCrunch article posted yesterday so it should be trusted.
2. Gmail has a new brilliant service, The 2-Step Verification, check it out and sign up for it here, it basically requires your password and then a code sent to you (or generated by a Google Authinticator app on your smart phone) to log in! Of course they've thought of a solution in case your phone was stolen or was not available. They also offer to generate you a specific passwords for third parties (your Android phone, Outlock, etc...) which is cool.
3. Remember to backup your phone contacts and stuff, manually or through an app. You don't want to have that moment where you realize you've LOST ALL contacts, images, etc on your phone.
4. Did you know that you can download a copy of your facebook?! everything; status updates, friends, your photos and videos, notes... You just need to go to Account Setting and click on the little thing at the bottom (download a copy of facebook data)
That's all I can think of, anything you do that you want to share?
Happy Hacks everyone :)