Stefano Garuti

This plugin allows you to directly embed Gmaps code in your posts or pages using the [gmap] shortcode.
HOW TO USE IT: 
When you are in the Write Post or Write Page screen, find the “Custom Fields” area. 
If isn’t already there, add a custom field named exactly “gmap” (without quotes) and copy and paste 
in the value field the whole code you obtained from Google Maps. 
Write anywhere in your post or page the “shortcode” [gmap]: when displayed on the blog it will be 
repalced with your Google Map. 
Save and publish. You are done!
UPDATE and NEWS at: http://www.wpmania.it/google-maps-mania-plugin/

GmapsMania

This plugin allows you to directly embed Gmaps code in your posts or pages using the [gmap] shortcode.

lborisov

LB Gmaps simply implements the Google Maps API, allowing users to create and style maps by their preferences. The thing that distinguishes this plugin from the others is that each change you make to your map is directly applied to a sample map right next to the map options.
<h4>LB Gmaps Needs Your Help to Improve The Overall Experience</h4>
The plugin is completely free and does not have any extensions you will be asked to pay for. That’s why I will need your help to add new and extend the current functionality of the plugin. I will be very glad to hear your feedback and ideas.
<h4>Installation and Setup</h4>
The installation is really simple. 
1. Upload the entire <code>lb-gmaps</code> folder to your <code>/wp-content/plugins/</code> directory. 
2. Activate the plugin via the “Plugins” menu in the WordPress dashboard. 
3. Go to the “Settings” page of the plugin and add your Google Maps API Key. 
4. Enjoy!

LB GMaps

Just another Google Maps plugin but simpler and with a live preview.

GmapsMania vs LB GMaps