Vindicator Siege Tank
First, the Blood Angel's 'Lucifer' engines make the Vindicator awesome. No other army in the game has a fast ordnance template that can instant-kill termies.
Second, this particular vehicle has a story. It is actually the FW version released way back in '02/'03 (and boy is there a story to that!). I purchased two Vindicators for my Dark Angels army (a picture of the remaining one is below) and used the 'Power of the Machine Spirit' upgrade on them. This meant that the tank could move 12" and still fire the ordnance. Unfortunately for me, that rule disappeared and my Dark Angels became far less effective and so were retired (to be fair, I also had a new IG, Ultramarine, and High Elf army to keep me busy in all that time). Strangely enough, that ability reappeared in a new way in the BA book, so I chose to repaint the Vindie to be red and mean.
Go go gadget repurposing!
also, here's the remaining 'ol Vindicator for the Dark Angels:
Notice the FW doors as well. And just so you know, those company markings were done by my hand! It's because when I try, my stuff comes out awesome. Sucks that I'm so lazy, right?