For mobile users, I really like Lookout to help keep your devices secure. I have been using it for quite a while on both Android and iOS devices and have been very pleased with what it provides for me.
The company is also very good at keeping users informed of potential problems and threats. This week, the good folks at Lookout contacted Android users with a warning about a new threat called "Stagefright". Below is the info from the email Lookout sent to its Android users, if you'd like even more info on the threat, you can get the lowdown from this Lookout Blog post.