For Christmas my wife purchased a DeLORME mapping program as gift for
me.
When I first installed it I did not care for it very much as it does not
go down to the level of detail I care for. Then I got the idea of trying
it to plot earthquake events. I found it to be a good tool for just that
job. 

The name of the program is "Eartha". This comes in two packages. One
with
a GPS and one without. With out the GPS I think it cost $30 - 40
depending
where you buy it.

You can plot by Lat/Lon and place a mark at that point, then change the
properties and have a different color marker for different magnitudes,
also you can change the tag for the marker.

What I do is make all Mag. 4's a blue mark, 5's are green, 6's are
yellow and 7+ are red. I tag it with the Mag/date.

Happy plotting