I needed a leader for my Death Guard forces, and a Daemon Prince fit the bill. The conversion potential of these things are crazy, and probably lend more to kit bashing than any other model IMO.
The new stats for DP's are pretty sick too, and they can usually whip about anything that you throw at them.
He's made from the body of a plastic DP, a Forgeworld Nurgle Troll head and arm, and a Hellbrute's power fist I clipped off. The tentacles I made using Green Stff Industries tentacle maker (which is awesome to have in your collection, especially if you play Nurgle).