I was wondering, which of the crew skills are complementary? Like mining and smelting in WoW, which gets the components for which?
Here's a very handy diagram for how the crew skills relate to each other.
Here's a direct link to the image article.
Edit: Update for patch 1.2
Here's a graph that delineates gathering, crafting, and missions.
—from SWTOR Crew Skills Diagram on Google Docs