What's app messenger
available on the iPhone, BlackBerry and Nokia phones allows you to send and recieve messages for free over your mobile internet/ wifi like bbm but also allows you to send voice clips , voice clipsand pictures free.
I think its fantastic :)
Its free on BB and Nokia as far as i am aware
and 59p on apple itunes
but its worth it as it uses your phone number to find contacts so no need to add anyone as it syncs with contacts already on your phone.
I assume BB and Nokias allowing downloading via their app store equivalents