Point Clouds File Formats (PCL)

I’m new to Point Clouds and I’m very enthusiastic about the whole concept so I searched a bit and found the Point Cloud Library (PCL).

http://www.pointclouds.org

I was expecting PCL to load most of the popular point cloud file formats but as far as I can tell, PCL seems to orbit around their own file format, the PCD.

I’ve been poking around but I'd like more insights on a few things:

What are the most commonly used point cloud file formats?

Which point cloud file formats are supported through PCL?

EDIT: Is there any collections of point cloud files available? Ideally, XYZRGB to play with.

Thank you,