To date, I think my most successful example of this is Kishin Hattori's signature. Of course, being my friend, I know exactly how he views his EVE character, and am hence able to recreate something beyond a ship and flames and glory.
My inspiration was actually the Lil Wayne album cover "Rebirth":
The most obvious change that needs to take place is substituting Kishin's avatar for Lil Wayne. However, there was a lot more to it than that. I really needed to change the whole feel of the piece. The album cover's golden scene portrays an almost lazy luxury, and Kishin is a much more down-to-earth kind of guy. He likes things that are traditional and classy - like antique leather rocking chairs and vinyl records (and his EVE character reflects the same attitude).
Therefore, the plush red carpet and gold needed to go. I faded out the fabric color on the couch, and replaced the golden gilded edges with a warmer, worn wood. A lot of the golds were replaced with grey, to give it an aged/weathered/weary look. However, in the album cover, the gold was the unifying factor, so if I was going to split up the colors, I had to find other ways to bring it back together again. Therefore, I threw gold and grey flecks into everything from the autocannon to Kishin's pants to the amp. I also accentuated the red in the couch, and used that color to create a patterned link across the image (from the wire on the far left, to his name on the far right). I replaced the guitar with Kishin's own favorite model, and then substituted Monster drinks for the wine bottle (it was either Monster energy drinks or Pepsi... but I thought the Monsters would be more mraaah!). The wolf pelt I left as an ode to the minmatar assault frigate. The guitar case needed to be shifted so the image would be more elongated than square. Shadows needed to be adjusted with the addition of new objects. And lastly, a giant auto-cannon was added to give a little reminder that he is in fact a pirate (and largely a frigate pirate at that). And then, voila!