It depends on the type of networking that he's looking to do.

Many of my friends in the arts are on Facebook, it's great for updating each other on current projects, but with all the little apps and such doesn't have a professional feel.

LinkedIn is geared towards business, but they have arts oriented categories and groups. If you're looking for something to attach to a resume or CV, linkedIn is better than facebook.

MySpace is still extremely popular for artists and those in show business, because of the extreme configurability of the site.

Redbubble is getting a lot more popular, particularly with Photographers and other visual artists as an easy way to create an online portfolio: www.redbubble.com/

I have no experience with Naymz. Took a look at the site. Any site that claims to be for professionals, to manage their reputations but spells the name that way I don't think is going to do well.

Linkedin is the only site worth pursuing. Facebook and myspace are toys by comparison. But it IS possible to meet people on facebook or myspace, so YMMV.