Now you can use DOM-element contents as a template. Just pass DOM-element id (like '#dom-element-id') and all those element's contents (innerHTML) will used as a template string.

underscore-template-extend.js

(function () {
	'use strict';
	var cache = {};
	_.templateDefault = _.template;
	_.template = function (str, data) {
		var match, elem;
		if (match = str.match(/^#(\S+)$/)) {
			if (!_.has(cache, str)) {
				elem = document.getElementById(match[1]);
				cache[str] = elem ? elem.innerHTML : str;
			}
			str = cache[str];
		}
		return _.templateDefault(str, data);
	};
}());