I have searched the web for some sort of software that will let me
enter zip codes only to map my customers in the the United States with
just a colored dot that I can show the areas.  I have 3 basic
customers with approx 2000 locations.  I know that there is expensive
tools that are hard to use.  I want it to be user friendl... like just
type the zip code in and BAM>> it charts it in the usa map.

I use Microsoft Streets & Trips, about $30.00 at Sams.

Maybe EVE from www.goosee.com will do that.

Try this tool. It was featured on The Screensavers a while back. Its
called ZipDecode and it is a simple little flash applet. It can zoom
in on individual zip codes all around the US and highlight a little
dot on a map for you. It can also zoom right in on a particular area,
as you are typing the zip code.

Unfortunately, it can only do one thing at a time. It doesnt store
zips to let you highlight multiple places. The only way I can think of
to store individual location highlights would be screenshots. So it
might not do everything you need.

http://acg.media.mit.edu/people/fry/zipdecode/

I'm betting something similar with the ability to store a list of zips
and highlight each place like putting a tack on a normal map would be
what you are looking for. Can't think of another tool like that for
free otherwise, at least not right now... :)

Microsoft Streets and Trips will do this.  You still might have to
select the general city to get this to work, but I use this
application in a very similar process.  If you decide to purchase it,
I will be glad to help.  I will monitor the site here to see if you
need further help.