On Google + I discovered The Library of Gaming Maps community and recommend you check it out. Currently, there almost 4k members with an active contributor base of artists who “……post and share maps they’re making, for the entertainment or aid of other gamers who may not have the chops or time to make their own!”.
Browse the posts and even if you are not a gamer you’re bound to find something of interest, especially if you are a SciFi or Fantasy fan. One can filter posts by topic which includes Fantasy (predominant), SciFi, Historical, Icons and Tokens and an eclectic Modern topic section, which contains a real grab bag of interesting posts.
Many members also link to interesting sites such as this one so there is enough here to stimulate the imagination of a game designer or game master.
Despite me this being a WW post, regular boardgames or old school hexagon maps are few and far between. Most contributors seem to be RPG players though I did find a nice WW3 themed map:
I like this guy’s art and dungeon designs:
And one from the SciFi section, a Star Wars “Knights of the Old Republic” map: