A great article on creating your own jQuery plugins/functions.
http://www.learningjquery.com/2007/10/a-plugin-development-pattern

Here’s a quick sample. Serves well as a base…

jQuery.fn.functionName = function(options, callback){
var settings = {
setting: "a",
callback: null
};
if (options) {
jQuery.extend(settings, options);
}
var jQueryParent = this;
var objIdx = 0;
this.each(function(){
jQueryChild = jQuery(this);
//put all your goodies here
//execute the callbacks
if (settings.callback != null) {
settings.callback(this);
}
objIdx++;
});
if (callback != null) {
callback(jQueryParent);
}
return jQuery(this);
}