I have a cheap Harbor Freight brad nailer and it does a great job of fastening my window trim and baseboard molding/etc. The only thing I don't like about it is that the point of contact is metal.
On multiple home improvement shows I see them attaching baseboard with a nailer that has a nice rubber boot (not just one of those crappy cover things that fall off). Awesome. However, these nailers are also mysteriously gigantic - I have no idea what they are - they appear to be larger than a framing nailer. I have also never seen one at HD/Lowes. What are these things?
And, regardless of whether or not the mystery humongous nailer is the answer - what's the best way to obtain a nicely-protected contact surface for trim work?