That's a good point. An individual can only get so angry...yeah. Never looked at it that way before. The Silver Surfer, as mentioned, does have the potential for unlimited strength seeing as he is not limited by anything other than his will. The Sentry I thought had the potential for unlimited strength, but apparently this is not true, as evidenced in WW Hulk #5 where he seemed to be maxed out in power. I am not sure what the base strength is of the Sentry, meaning he must have a lower starting point because he had to "amp up" to go toe to toe with the Hulk. I am also unsure of the Surfer's base strength; FF #48 shows the Surfer increasing his strength to match that of the Thing, who then was about an 85 ton guy. As earlier stated, he seems to have the potential for unlimited strength.
Classic Thor was also finite in strength, save for use of the belt of strength and those rare occasions when he was overcome with "warriors madness", increasing his base strength tenfold. However, Thor's base strength, although static, was/is astronomical as illustrated by the throwing of the Odin-sword through a celestial's armor, lifting of the midgard serpent matching the strength of a very pissed off Hulk on a few occasions. Surfer, Hulk (whose base strength is in the 70 ton range...)and maybe the Sentry would all have to amp up to equal the base strength of Thor.
However, with the Odin-force (a blend of mystical and cosmic energies that augment all his attributes), Thor also has the potential for unlimited strength. I suppose what I'm suggesting is that Thor's base platform of strength is much, much higher than Hulk's, Surfer's and possibly the Sentry's and is no longer "static", but like the aforementioned three, is unlimited. The difference is, Thor starts much higher than the other three. Thor may be the new king of strength at Marvel comics (don't get too excited Thor fans, Marvel will probably find a way around this to accomodate the more popular Hulk...).
And no, I have not forgotten about Hercules who has always given classic Thor a run for his money in raw, brute strength. Hercules' strength, although way up there with Thor's, is static and he does not have the potential for unlimited strength.