I have two projects here.
Radio (GitHub - gryor/radio) is a library for transmitting and receiving data using a radio. Currently it's supporting only those cheap transmitters and receivers found on ebay. I made this library after I was unable to get VirtualWire to work correctly and after noticing how badly RCSwitch was coded. Also, compared to RadioHead RH_ASK, this is a lot more simple library and requires less memory.
It's coded in C and is supposed to be cross-platform and cross-radio (please contribute similar interfaces for different radio modules). The example uses 433 Mhz radio modules and an arduino pro micro.
Itikka (GitHub - gryor/itikka) is a broadcasting radio repeater based on the Radio above. It's supposed to listen for radio transmissions, keep a history of transmissions' checksums and retransmit only those messages that are unique. History items will timeout to allow retransmission. This will extend the distance of the radio transmission of other devices.