1. A method for collaborative annotation of a document, the method comprising: generating, by a host computer, a graphical user interface (GUI) that displays a document to annotate; transmitting, by the host computer to a plurality of client computers, the GUI; establishing, by the host computer, a plurality of real time communication modes between the client computers, each communication mode including communication channels between all client computers; receiving, by the host computer from of the plurality of client computers, a plurality of correct annotations and incorrect annotations entered into the GUIs at the client computers, each correct annotation and incorrect annotation identifying a span of words in the document to annotate and including an associated annotation type, the correct annotations and incorrect annotations identified by a coordinator; identifying, by the host computer, conflicts between the received correct annotations and incorrect annotations, wherein a conflict is an associated type of one of the annotations does not match the associated type of another annotation or the span of words is associated with fewer annotations than the number of the plurality of the client computers; generating, by the host computer, a summary by type including each correct and incorrect annotation; updating, by the host computer, in real time, the GUI to include for display the received plurality of correct and incorrect annotations and inter-rater agreement statistics indicating the level of agreement between the correct and incorrect annotations received from each client computer and further including for display the identified conflicts between the received correct and incorrect annotations; and transmitting, by the host computer to the plurality of client computers, the updated GUI.