I am currently developping an "Internet of things" platform, in order to connect data from physcical devices, in the same spirit than Xively but with different features.
The platform support http (rest API) and MQTT (but not yet documented) and provides some cool features, like a live dashboard and is of course free.
Would be interested to have some early adopter and feedback, to know what you really would love in such platform
The project is here:
and a live version is here:
http://www.opensensorcloud.com
Any feedback welcome