Apps for new users

hi again.

So i just got a xperia L recently & i was wondering what apps should i download..
( all free atm.. )
For browsers, i have chrome & opera mini pre-installed.
For Social Network apps, i have the facebook/twitter/whatsapp & palringo app
For Utilities app, i just downloaded the Advanced task killer by rechild. is this good & safe ??

I need some good suggesstions for Multimedia, Camera editing & security purposes app( like any tracking apps if my phone gets stolen ).

Any other suggesstions are also welcome.

thanks.