Interesting. After looking through some of the guides I think I still prefer the RHS site though, there's nothing like 200 years of experience backing up a guide! It will be useful if it expands though, so much information is just lost in gardener's forums archives...
The technological explosion in gardening is interesting though. There's a company local to me who are doing aerial surveys for local farms using a quadcopter+multispectral camera.
I'm currently working on a long duration above/below ground WiFi temperature sensor (MSP430/ESP8266 based) to satisfy my curiosity; I'm having trouble figuring how to get the data to a web-page though, having never done any web development before!