I have been using the Flexible Upload D3Z Edition WordPress plugin for a couple years now on various sites that I work on or manage. To me it provides a much easier interface to upload images while building thumbnails on the fly than the default WordPress image media upload. The issue is the Flexible Upload D3Z Edition plugin has not been updated since WordPress version 2.6.X so it has broken on more than one occasion. So when upgrading to WordPress 3 recently it broke the Flexible Upload D3Z Edition plugin and below I describe how to fix the plugin so it will operate without issue in WordPress 3.X.
SimpleViewer offers a great way to display your photo albums on WordPress combined with NextGen Gallery in an easy to browse format. The arrows display out to the sides of the thumbnails when you only have one row configured however you must have the source code that comes with purchasing the product to modify the source and move the arrows to the sides if you have multiple rows of thumbnails configured. I figure it is worth the money if this is a gallery you are using as it would cost much more in time to develop the gallery yourself.
The default location of the arrows is shown below in the image.