I'm using an N95 8Gb so Trapster, with its positioning functionality is a very good pick for me - I'm all about any app that enables me to take advantage of the built in GPS on my handset! The app enables me to see on a map where police hang out with speed traps. Better yet, it has social provisioning enabling me to add locations where I know police frequently hang out trying to nab speeders etc... A truly fun and useful app! 

Trapster is know as the "speed trap sharing system" - see more at http://www.trapster.com/ or search Trapster at http://store.ovi.com - FYI, users can also visit the TrapMap using their PC, enabling them to view traps before you head out of the home or office! Twitter users will be glad to know that you can also follow Trapster @trapster

About Trapster:
Trapster ®, your mobile phone alerts you as you approach police speed traps and safety cameras. Join a worldwide community, over ½ million users strong! It's the modern day replacement for CB radios and flashing headlights at other drivers to warn them of a speed trap ahead.