For everyone who's been wondering what do I wear to a wedding where Firefly-Inspired costumes have been requested, here's some help. First visit Can't Take the Sky for screencaps from various episodes - a great way to get a general feel for the costuming. Also check out The Costumer's Guide to Movies. They have a section dedicated to Firefly.
To get you thinking about costumes, here's an Inara-inspired look I put together. River and Kaylee-inspired looks to come later.