Minimal meteor reactive variable example. http://meteorpad.com/pad/kajGdYLfTrEkE5NtL

meteor_reactive_var.html

<template name="meteor_reactive_var">
  <div>{{count}}</div>
  <button>Increment Count</button>
</template>

meteor_reactive_var.js

// Initialize reactive variable.
Template.meteor_reactive_var.created = function() {
  this.count = new ReactiveVar(0);
};


// Expose reactive variable to template.
Template.meteor_reactive_var.helpers({
  count: function() {
    return Template.instance().count.get();
  }
});


// Listen to event to update reactive variable
Template.meteor_reactive_var.events({
  'click button': function(e, tmpl) {
    var currentCount = tmpl.count.get();
    tmpl.count.set(1+currentCount);
  }
});

Thanks for the quick example.