I studied this guy's website on exposing "Should you believe in the Trinity", extensively. Although I very much appreciate the volumes of key reference materials that he puts out there, and I also consider myself to be a Trinitarian, I think this guy is basically a "kook". His arrogant, childish, pouting attitude permeates his whole commentary and really detracts from the credibility of his whole site. The arrogance actually exceeds that which you encounter in the pages of the Watchtower. It's like some JWs made him cry and he's gonna show them, by golly.
I think that one of the best scripture-based references on the Trinity is "Reasoning from the Sriptures with the Jehovah's Witnesses" by Ron Rhodes. This deals with the divinity of Christ, Trinity, personality of the Holy Spirit as separate topics but addresses most of the key Biblical arguments presented by the WTS in a pretty effective way.
As far as an expose goes, this website provides the most complete reference material I've seen. It's more extensive than Angel Arellano's book. The problem is you have to wade through all this guy's comments about the WTS being satanic and stuff but if you're willing to take the time to cut-and-paste alot of the relevant material in to a summary form (as I have), it is pretty amazing.
As for a history-based reference, this site is pretty good: http://www.freeminds.org/doctrine/trinity.htm
Also, Randy Watters' book, "The truth shall set you free" gives a really good historical and scripture based take on the doctrine.