Over the course of my Frontier ownership, I've come to love this website. I'm not 100% certain by whom it's operated/owned, but the forums have several astute guys/gals who appear to be factory trained techs and who are quite helpful.
Got a trouble code? Look it up in the forums, you'll get brilliant information. You'll even find discussion going on about the issue, and I doubt I need to convince you of that value. Download service manuals, TSBs, and recall notices; read/write dealer reviews; research the cost for a repair; what-have-you.
While I've never had trouble taking my Frontier to the dealership for TSBs or warranty repair, having the knowledge (gleaned from that website) behind some of my problems in the past at most gave me an advantage, and at least made me feel comfortable with my service agent.
I'm going to request this become a "sticky" because if you don't know about Nissanhelp.com as a Nissan owner, you should.