Hi,
I was just wondering if there's anyway to do that ghost voice effect in Vegas using the built in plug-ins.

The effect I'm talking about can be heard in 13 Ghosts. The voice starts out backwards and swells forward and has a kind of a flange type sound to it. I can't for the life of me figure out how to do that effect.

Anyone got any ideas?

I don't know about 13 Ghosts, but this sort of thing is usually done with a reverse reverb coupled with flanging, phasing, delay, and/or chorusing.
You could easily do this with a doubled track (one reversed), or get a plug that has reverse reverb as part of it's feature set. This would be the easiest method, IMO.