First off, you can create your own custom Google Maps, you will need a free Google account for this. you can create plaemarks, colored lines, colored shapes, and what ever icons you want to use. The only downside I see to this was that you can not host the map yourselft, you can link to it or embed Google's code into a frame on your website. More Info: http://maps.google.com/support/bin/answer.py?hl=en&answe
Example Map1: http://maps.google.com/maps/ms?hl=en&safe=off&ie=UTF
Example Map2: http://maps.google.com/maps/ms?hl=en&safe=off&ie=UTF
Secon, take a look at MapBuilder.net. I have used this service for more advanced maps, and it also lets you store pretty much all the map coding on your own website. They have a built-in geocoding tool that lets you type in an address and they will plot the property on the map for you using it's lat/lon. More Info: http://www.mapbuilder.net/index.php
Example Map: http://www.crossroadsrealtynj.com/home/communities/adult-community-
mapquest.com You can put in up to ten addresses on mapquest.com. It's very nice, once you've entered the addresses, if you don't like the order they're in, you can move the address up or down and put them in driving order.