Wow, didnt know you kept updating this thread.
Well Ill comment on whats incommon in all the sigs.
Theres two things that need work. First its the text, try blending it in some more and not just leave it like that, experiment.
And then there is the focal point, its way of to the edges. Go search google for a quick tutorial on the rule of thirds.
EDIT:Heres a wiki one.
http://en.wikipedia.org/wiki/Rule_of_thirds