Yes, you should do a log plot
plot(Visits ~ Day, data=feedback,log="y")

but I prefer ggplot
qplot(Day,Visits, data=feedback,log="y")

I prefer ggplot2 too, but due to an ill-considered invocation of fdupes I yesterday trashed my local R installation, among other things, and haven't had time to make things right (I was busy with the Sheep Marketplace fallout and then writing up the post).
For the full writeup, see http://www.gwern.net/About#anonymous-feedback