Quietly Unlocked [Flashable]
I've made a new splash screen for the HTC Sensation from a template posted on the XDA forums. I'm pretty happy with it and if you want you should download "Ben Brown" font from DaFonts and personalise yours like this:
As you can see, it looks pretty good using the font and you can have a splash screen personalised to you. You'll need to grab yourself "GetSplash" to convert any personalised versions you create, you can get it from here: Get Splash
To flash, you need to reboot into the Bootloader, make sure your drivers are installed and the type the following into command prompt:
fastboot flash splash1 yoursplashfilename.img
This will push the splash file to your device and overwrite your existing one.
UPDATE 02/03/2012: Due to the changes to the ICS firmware, some HBoot's will not allow you to flash using "fastboot flash" anymore. There is a workaround which can be found here: [How To] Flash a new Splash image with Latest FW