It looks like there's a contender for the most flexible 40k vehicle kit around. Spikey Bits has posted a fantastic conversion using the Valkyrie kit. And Rob is right, the possibilities are almost endless. From generic jet to Thunderbolt to Arvus Lighter, you can pretty much make anything Imperial that flies with this kit.
With all the new plastic released in 2009 by GW, the kit-bashing possibilities are endless. What's on your 2010 kit-bash to do list?