I saw Damon Minor hit two awesome home runs at Pac Bell last September, including one that would have been in the water if it hadn't hit the top of the foul pole. At the same time it's clear at a glance that the guy can only play first base. As you say, he's a good solid hitter looking for a job. I think the Giants should trade Snow now while his value is high, and tell Minor that he's the first baseman. He's 27, now is the time to get him into the lineup.
Snow is below average as a first baseman in the modern context, at least offensively.
Of course, J.T. provides outstanding defense at first base, which is why he stays in the lineup despite mediocre hitting numbers. Personally, I think his combination of below-average hitting and excellent defense balances out to make him an average first baseman. Unless you believe that Snow's defense saves 300 runs a year, it's hard to make the case otherwise. I have to admit, he's one of my favorite minor leaguers, since he's better than some people who have jobs, and is a superior prospect to his more-heralded brother Ryan. I was prepared to write that the Giants should have been willing to give Damon a shot over Snow.