creating a list of matrices or data frames

Hi all,

How would you create a list of data.frames within a loop, then bind all
the elements of the list using rbind?

take this example of matrices with differing numbers of rows

for(i in 1:3){
assign(paste("s",i, sep=""),matrix(data = NA, nrow = i, ncol = 3, byrow
= FALSE, dimnames = NULL))
}
s1
s2
s3

I want to bind all the matrices at the end with do.call(rbind...) 
rather than listing all the elements manually with rbind(s1,s2,s3...)
and so on.

thanks in advance.

Simon.