I find building a product using a 3rd party API can be totally awesome or a complete disaster. In my case I had two experiences that stood out: RDIO: These guys

I find building a product using a 3rd party API can be totally awesome or a complete disaster. In my case I had two experiences that stood out: RDIO: These guys are awesome. Their API is awesome, their support of devs who build on it is awesome. Their product is awesome. Kudos to Ian who works on it. We built Anthm on this and it has worked out great! FreshBooks: These guys made me furious. We found that there were no good OSX based timers for this product so we built one. In the end they refused to put us up on their site, each time with a different excuse (we have promised exclusivity to this other app, or we are changing our app system). The developer relations guy was just a total jerk. In the end they asked us to change our name because they did not like it and even after immediately doing that, no love from them. In short - it is getting tough to base a business on any of these third party API's that can change under your feet - yet there are still some out there that are tremendous.