Over at Sleeds.org is an interesting movie how they made a building, the process started with PDF, exporting it with Adobe Illustrator into SVG, this was processed by a script to get LSL snippets posted into a notecard and then got finally rezzed in SL.
This looks much like e.g. blender to prim, but it's impressive, none the less, though I guess if you really want to build good things you need so stuck up with the client. Period.