[R] Adding Lines to Plot

[justin rapp]

This seems like a question that I should be able to answer on my own
but after looking at the documentation I cannot seem to find the
correct method.

How do I add lines to a bar plot that extend from the vertical axis?
For example, my vertical axis is numbered in increments of 10 and I
would like these to go across the whole graph.

Also, is there a way to have R label the value of each bar so that I
know the value of each factor that is being plotted?

Thanks in advance.

jdr