Don't normally post free apps from the Ovi store, but this one I felt was a bit of a gem!
It's a lock screen app that lets you unlock the screen by swiping a 'maze' defined by you. Great for stopping someone going through your phone if you leave it somewhere for a moment. Also liked the fact the lock screen shows the date and time clearly.
Direct link: http://store.ovi.com/content/68486
(not sure why hukd blocked the link... apple store links work :S)