mlens is a jQuery plugin that simplifies creating this magnifying glass functionality so much.
It has some parameters like the shape of the lens (circle or square), lens size and the options for customizing the border.
GSInnerZoom is a jQuery plugin that permit you to do an inner zoom or magnifier inside an image.
Cloud Zoom is a free jQuery image zoom plugin, a comparable alternative to products such as Magic Zoom. Compared to the popular jQZoom plugin, Cloud Zoom is smaller, has more features and more robust compatability across browsers.
Also Picbox WordPress plugin is now available.
Mosaiqy is a jQuery plugin for viewing and zooming photo working on Opera 9+, Firefox 3.6+, Safari 3.2+, Chrome and IE7+. Photos are retrieved from a JSON/JSONP data structure and randomly moved inside the grid. All expensive animations are taken over by your GPU on recent browsers using CSS3 transitions, minimizing the CPU overhead.
jQuery Gantt Chart is a simple chart that implements gantt functionality as a jQuery plugin. Plugin uses AJAX to retrive JSON data and render them as Gantt chart with many features such as zooming or paging.
Zoomy is a quick and easy plugin that will zoom into a picture.