My dd uses Singapore Standards Edition and EPGY. Singapore is matched to CA state math standards, which is supposed to be advanced compared to other states. It does seem to run about 1/2 year ahead, as has been mentioned. EPGY seems to be about at level, though that would depend on your state. (The two areas that EPGY seemed to introduced earlier were set theory and variables)

Gamewise-
My DD used Thinkmath! to play around with in K. It's Harcourt's website, so you can select your state and the games will appear in grade level order, correlated to your state standards. He/she can work at any level up through grade 5. There's a great variety of games in all areas of elementary math.

http://www.hbschool.com/thinkmath/choose_state.html

Curriculum wise, Miquon math and cuisennaire rods laid the most thorough understanding of the relationships in mathematics I could ever hope for. We did that before Singapore.