A remark on variable numbers of argument ...
A silly example to illustrate variable numbers of arguments. The ... get put in a list and written out to the screen. Then those same arguments are passed to the plot function. 
function(x, y, ...)
{
        opt.arg.list <- list(...)
        i <- 1
        for(arg in opt.arg.list) {
                cat(paste("Arg", i, " = ", "'", arg, "'", "\n", sep = ""))
                i <- i + 1
        }
        plot(x, y, ...)
}
Other places to look: