Here are some links to some points of interest.

Shops:
Here are some shops that sell some cool Firefly/Serenity themed swag, among other things.

Legendary Leatherworks - Cool leather working site selling everything from lanyards and belts to mugs and armor. Official supplier of the 76th Bn's D*Con Lanyards.

Out to the Black Outfitters

Serenity Verse

Groups/Informational:
Here are some various sites for information or discussion groups.

76th Battalion Proboard - Dedicated message board for the 76th

Bedlam Bards

Firefly Fans

Serenity Stuff

The 76th on MySpace

Ballistic Mesh Sleeves Tutorial (also found on Uniform Page)