http://www.engageny.org/mathematics - This is New York's official math curriculum website. They adopted the Common Core a few years early and have been building their own curriculum. Now we get to "borrow" it!
http://www.insidemathematics.org/index.php/mathematical-content-standards - Inside Mathematics is a group of educators and experts who have pooled their resources to create some impressive curriculum and training materials.
http://robertkaplinsky.com/lessons/ - Robert Kaplinksy has created dozens of engaging videos with associated questions to help teach mathematical concepts. They are well-organized and very entertaining, and go from Grades 2-12!
http://emergentmath.com/my-problem-based-curriculum-maps/ - These are very impressive curriculum maps for Common Core mathematics. They include pacing guides as well as Google Drive documents containing hyperlinks to external curriculum. Sorry, but these are only for 6th Grade and up.
I hope these help out - comment and let me know if you have any other resources!