I felt this thing crawling on the back of my neck.

This weekend I was riding through some 4-wheeler trails when I drove through a spider web. The web became entangled around my boonie hat, so the hat came off real quick. This type of spider has been discussed before. Anyone want to tell me its name and how bad is its bite??

Can someone refresh my memory as to what kind of spider this is? Please post whether you knew the answer or if you looked it up.