Nice little snippet I found on the 'Net.
Get directions to your showroom/place of business with Google maps. Add this short form to your website, enter an address and a new window pops up with driving directions on a Google map. Enter no address and just a map of your showroom/place of business opens up.
1) Replace 350 5th Ave New York... with your business address, put your business name in the parentheses.
2) If you don't want the map to open in a new window, remove the target="_blank" from the form action line.
Code:
<form action="http://maps.google.com/maps" method="get" target="_blank">
<label for="saddr">Enter your location</label>
<input type="text" name="saddr" />
<input type="hidden" name="daddr" value="350 5th Ave New York, NY 10018 (Empire State Building)" />
<input type="submit" value="Get directions" />
</form>