I've been very busy working on Superfastmatch, but I wanted to spend a day or two trying out a few ideas with the Fusion Tables API and static hosting on App Engine. One of the interesting things with App Engine is that you get 1GB a day of bandwidth for free. If you use static files, then no CPU cost is incurred, effectively giving you a high performance CDN for zero pence!
Fusion tables are intriguing because they offer spatial query processing and very thorough Google Maps integration. What this means is that you can completely avoid setting up any database infrastructure such as PostGIS and any tile generation services like Tilestache.
The app is now live, so I'll soon see if it gets picked up for any Google search keywords. Looking at autocomplete it seems like Gyms Near Me is the top term so maybe it will get picked up! In the future I might also look at feeding in gyms for global locations and saving map positions like Gyms in London.