An implementation of a jQuery carousel.

jquery.newscroller.js

jQuery.fn.newScroller = function(_options) {
    if (typeof _options == "string") {
        var args = Array.prototype.slice.call(arguments, 1)
        return this.each(function() {
            var $this = $(this)
            data = $this.data("newScroller")
            if (_options in data.functions)
                data.functions[_options](args)
        })
    }
    return this.each(function() {
        var $this = $(this)

          , options = $.extend({ itemSelector: "ul li", prevContent: "prev", nextContent: "next", items: 1, interval: 5000, speed: 500, width: 0, height: 0, wrap: false, autoPlay: false }, ((_options && (typeof _options == 'object')) ? _options : {}))
          , $elements = $this.find(options.itemSelector)
          , $controls = $("<div class='controls'></div>")
          , $nextEl = $("<a class='next' href='javascript:void()'></a>").append(options.nextContent)
          , $prevEl = $("<a class='prev' href='javascript:void()'></a>").append(options.prevContent)
          , data = {}

        $this.data("newScroller", data)
        data.properties = {
            current: 0
            , interval: 0
            , paused: !!options.paused
        }

        function option(key, value) {
            options[key] = value
        }

        function play() {
            data.properties.paused = false;
            if (data.properties.interval) {
                clearInterval(data.properties.interval)
                data.properties.interval = 0
            }

            data.properties.interval = setInterval(next, options.interval)
        }

        function toggle() {
            if (data.properties.paused)
                play()
            else
                pause()
        }

        function pause() {
            data.properties.paused = true;
            if (data.properties.interval) {
                clearInterval(data.properties.interval)
                data.properties.interval = 0
            }
        }

        function next() {
            data.properties.current++
            if (data.properties.current > $elements.length - options.items) {
                if (options.wrap) {
                    data.properties.current = 0
                }
                else {
                    data.properties.current = $elements.length - options.items
                }
            }
            else {
                update()
            }
            if (!data.properties.paused)
                play()
            return false;
        }

        function prev() {
            data.properties.current--
            if (data.properties.current < 0) {
                if (options.wrap) {
                    data.properties.current = $elements.length - options.items
                }
                else {
                    data.properties.current = 0
                }
            }
            else {
                update()
            }
            if (!data.properties.paused)
                play()
            return false;
        }

        function update() {
            $elements = $this.find(options.itemSelector)
            animate($this.find(options.itemSelector + ".active"), $elements.eq(data.properties.current).addClass("active"));
            if (!options.wrap && data.properties.current <= 0)
                $prevEl.addClass("disabled").attr("disabled", "disabled")
            else
                $prevEl.removeClass("disabled").removeAttr("disabled")
            if (!options.wrap && data.properties.current >= $elements.length - options.items)
                $nextEl.addClass("disabled").attr("disabled", "disabled")
            else
                $nextEl.removeClass("disabled").removeAttr("disabled")
        }

        function animate(oldEl, newEl) {
            switch (options.fx) {
                case "fade":
                    oldEl.stop(true, true)
                    newEl.stop(true, true)
                    oldEl.fadeOut(options.speed)
                    newEl.fadeIn(options.speed)
                    break;
                case "shift":
                    $elements.parent().eq(0).stop(true, true)
                    $elements.parent().eq(0).animate({ left: -newEl.position().left }, options.speed)
                    break;
                default:
                    oldEl.hide()
                    newEl.show()
            }
        }

        data.functions = {
            animate: animate
            , next: next
            , prev: prev
            , pause: pause
            , play: play
            , update: update
            , toggle: toggle
            , option: option
        }

        $prevEl.click(prev)
        $nextEl.click(next)

        $this.append($controls.append($prevEl, $nextEl))

        update()

        if (options.onLoad) {
            options.onLoad.call(this)
        }

        if (options.autoPlay)
            play()

        return this
    })
}