This looks like a decent amount of work went into it.<p>Can the user change the differential equation being shown? By the way, what equation is being shown here?<p>In my browser (Safari 5.0.6), initial conditions get rounded down to nearest integer. E.g., y(0)==1 graphs the same as 0, y(0)==1.8 graphs same as 1.<p>You might re-think the title of the "go" button, since it doesn't really "go" anywhere. Maybe "set"?