While this in and of itself could be helpful and cool -- especially for finding additional information or reviews about a location -- Sysomos (the company that created FourWhere) has also used intelligent matching to combine similar venues. So if a location appears as one name on one service and under a slightly different name on another, FourWhere will merge them into one entry.
That technology doesn't work reliably 100% of the time (I was able to see additional Foursquare entries for the same restaurant, even though the addresses were the same), but a certain amount of that is due to duplication issues on the part of the location services.
The site itself remains highly usable and this is a great resource for people looking to find more information about a venue, without needing to log in or belong to all of the different location-based services. It would be really cool if there was a mobile or tablet-based version of FourWhere, although we understand that might be difficult from a development standpoint.
What do you think of location-based mashup services like FourWhere?
