Not bad. Great use of color, and the city skyline is magnificent. One thing I would have done differently is use a more modern font, but other than that, it's a beauty.
American spelling, eh? Saviour* Good concept but looks a little over-saturated to me. I like it though.
Keep in mind that we had stupid Daniel Webster remove all the U's in many words. Ex: Labor=Labour Color=colour.
Wait, what? What does Daniel Webster have to do with this? If you are thinking of the "Webster dictionary," that was originally compiled by Noah Webster, an early advocate of educational reform in the mid-1800s... Anyway, as for the sig, I think its very nice, but I wish the skyline was visible in the left side of the image as well... it looks a little odd to have a realistic skyline on one side of Spiderman and abstract C4Ds and effects on the other side. The right side, though, is very well done, with really nice transitions from Spiderman to Spiderman's head to the skyline. I would change the font to something a little bit darker, and more simple; the current text doesn't really match the sig. You might also consider slightly changing the saturation of the skyline and changing the coloring of the abstract stuff, because Spiderman looks more saturated than the background and the C4Ds don't have quite the same coloring either. Overall, good work.
I don't think it's that big of a deal. I happen to prefer labor over labour. It saves time, ink, and graphite.