Yikes! The continually changing numbers drives me crazy. Thanks for the tip, but I think I'll stick with just using ":13" to go to line #13... I guess there is some benefit if you do a lot of yanking/cutting based on lines, rather than some magic matching or such. But for now, relative line numbers is not for me.

For (a little) more, see:

http://vim.wikia.com/wiki/Jump_to_a_line_number