Just launched: a new relationships Web site that mashes up Craigslist personals with Google Maps to show you exactly where you can find people who want to “hook up” in your local area.

The service, dubbed HookupMaps.com (remember that very first Google Maps/Craigslist mashup – HousingMaps.com?), opens with a disclaimer: “This site may contain explicit content not suitable for people under 18 years of age.”

That certainly seems accurate. If you know the “casual encouters” section on Craigslist, they range from enticing to erotic – emphasis on the latter. But if the goal is to help people find hook up relationships close to home or work, the service may actually be useful.

HookupMaps.com has a simple interface – a Google Map with little hearts and numbers indicating how many potential hook ups there are in a particular area. The service covers New York, Washington D.C., San Francisco, Los Angeles and San Diego. In San Francisco alone there are 1000s of listings.

Clicking a heart opens a text list to the right of the map with all the corresponding Craigslist personal ads, displayed 50 to a page. There are filters – m4w, m4m, w4m, w4w – and users can search by neighborhood or keyword.

San Francisco computer engineer Josh Liptzin is behind the site. He says he coded it to put a fresh face on Craiglist’s stark design which he called “so 1996.” In the last week, the site has had an impressive 10,000 unique visitors, Liptzin said.

HookupMaps is more of a gimmick than a serious revenue-generating site. And, like mashups before it that involved Craigslist, it’s likely to get taken down (probably sooner than later now that we’ve written about it here!) In the meantime, we think it’s pretty clear that larger sites like Match.com have little to fear.