LDD has a hidden Extended mode that lets you recolour bricks, even to shades that don't exist as real bricks. It also unlocks loads of bricks that aren't available in the normal modes, including parts from licensed sets. It's pretty awesome.
EDIT: While I'm bumping this topic, quick preview of my current project- Kanalet Castle. Still a lot of work to do on this one. I took the opposite approach to perspective from what I did on Mt. Tamaranch- all the walls are straight, and I made up ground surface for the tiles that should be hidden behind them.
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"I'm Commander Shepard, and you're standing in the biggest library in Citadel Space. Look me up."