Ghostbuster costumes, like many others, tend to evolve over time.  So far I've built a proton pack and Ecto goggles.

Update: Dragon*Con 2011 pic:

Here I am actually wearing it (right before DragonCon 2008):

In 2009 I marched with the "PKE Surge" Ghostbusters contingent in the DragonCon Parade.  We even got a pic on the CNN website.  Yep, that's me behind the guy with the hat.