I learned a great term this morning via this talk: The "Geocities of Things". Frankly, half of the little Arduino projects I do are probably Geocities-of-Things level; certainly not professional, but then again, that's kind of the point.

SkyNet

http://skynet.im/

Dweet.io

https://dweet.io/

BERG Cloud

http://bergcloud.com/

Node-RED

http://nodered.org/

This is a step past the others. SkyNet, Dweet.io and BERG Cloud are all transports with varying degrees of sophistication. Node-RED is an IBM Research project that lives on top of MQTT. It's not interested in transport as much as analysis. It's a tool to create a processing node.

http://iot-bay.org/