Last year, we covered WeddingMapper.com, a free service where you can create online wedding maps for your guests.
If printed maps are more your style, idoweddingmaps.com might be more what you're looking for. idoweddingmaps.com offers four styles of maps, which you create online by filling out some information about you and your event. You can choose to have a PDF e-mailed to you, or have your maps printed and sent to you to include in the invitation.
We recently attended a wedding where the map was created on idoweddingmaps.com, and it was very clear and attractive, and printed on good quality paper.