Good plugins for Sony Vegas?

[DaRealBoss]

I've got Sony Vegas and use it from time to time for editing. Most of the features are pretty much included in the core build. However, I want to do some experimenting with different tools. That's why I'm creating this thread. Anyone here who uses Sony Vegas, can they recommend any plugins that I can use and play around with to enhance video editing quality? I would really like them to be free but if you have paid ones, then leave them below too.