Lookout Mobile Security |
One of the most popular app in the Android market, Lookout, claims to safeguard your phone from viruses. As a bonus, it allows you to take a backup of the data as well as locate your phone through a web browser in case you lose it and the finder/thief has not switched off the device. It's available in both free and paid versions.

AntiVirus Free |
This one is from AVG, the security firm that also offers free anti-virus software on PC. Apart from the usual anti-virus capabilities, AVG offers backup assistant, phone locator, app locker and task killer. This app is available in both free and paid versions.

Norton Mobile Security |
Symantec is trying to cash in on the strong reputation it has built on computers. This app is still in beta and hence free at the moment.

Bit Defender Mobile Security |
Another biggie that is now focusing on fighting malware on smartphones. Just like Symantec's app, this one too is in beta and free for use.

Kaspersky Mobile Security |
The only security app here that costs money. Considered to be among the best when it comes to fighting virtual threats on PC, Kaspersky believes it can make a mark on smart-phones too. As added features over free apps, Kaspersky offers call and SMS junk filter and privacy protection for each contact in your phone book. Price: Rs 448.

NOTE:
All apps listed above are for Android. Similar software, however, is available for Symbian and BlackBerry phones. Anti-virus apps are yet to make a mark on iPhones, though the K9 Web Protection Browser can be used for safe surfing on iOS devices. K9 is free at the moment.