I have turned on 'markers' today so you can put little icon's on your house, shop, giant sheep statue, etc which will show up on the map
the way to make one is pretty simple, place a sign with the following:
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[dynmap]
icon:house
MarkerName
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Below are a list of icons you can choose from, just be sure not to put a space between the colon and the name
And please put the MarkerName (Which can be whatever you want.. like 'Bobs House' or 'WoolMart') on the last line of the sign
If you want to remove the marker, just destroy your sign.