Anyways, if you don't anticipate credit for EPGY/CTY (note, most prestigious universities don't award credit for EPGY), the
http://www.artofproblemsolving.com/C..._Classroom.php courses give you a lot more value out of your money (I've heard a lot better reviews of it). You get to interact with peers and you get a lot more instructor feedback (plus a virtual classroom)
There are other helpful sources too:
http://www.artofproblemsolving.com/F...c.php?t=133510 http://www.artofproblemsolving.com/F...ic.php?t=40984
But go for CTY Multivariable Calc if you aren't that comfortable with your math ability (since those taking AoPS courses tend to be VERY math-oriented). If you're more into the other sciences and just happen to be ahead, you might get intimidated by the AoPSers (and AoPS standards).
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EDIT: interesting, freeflyer and 09xoxo are both SSP acceptees. ^_^ I just looked through the SSP threads. Ah, the times. Heh, I posted 73 times in the old 2005 SSP thread but I was a sophomore rejectee. I was thinking of doing EPGY multivariable calc during that summer but got into a math program.