A quick customization I have on my E71 - using SmartSettings and MagicKey, I can lock my device using the PTT button on the right side between the volume keys and I can unlock using a double tap on the UP-UP dpad. Here's how it's done;
In SmartSettings, set your "Easy lock" to the Red Call End button, push it twice and wait for the timeout. Set your "Easy unlock" to the UP button on the dpad, again push it twice and wait for the timeout. Save and next step. Open MagicKey. Create a new Application and select as "Home Screen" from the list.
Hit right on the dpad and create a new keymap. Add a new keypair, press the Green Call button then the PTT button, hit Ok. Now press the Green Call button and the Red Call End button, push Ok. You should now have this;
Now when ever you tap twice on your PTT button while on the home screen, your device will lock.
I'd also like to share with you some screenshots of my favorite and most used themes with links of where to get them. The theme above is what I am obviously currently using;
Nokia Neon Noise