I made this Thumbnail Manager utility class to make things easier for developers. Still has limited features but planed to increase it in future.
This Utility class makes easy way to developers to create the thumbnails, can be used in image gallery.

Features:

Aligning the thumbnail vertically or horizontally.
Each thumbnail will preload of its own.
Ability to set preloader color.
Easy to set cachebuster.

Next Version Features:

Resize the image proportionally.
Aigning image in Row and Column.

Usage:

ThumbnailManager(Array of URL, ThumbnailManager.HORIZONTAL_ALIGN,Height,Width,Spacing,Preloader Color ,CacheBuster)

Example:

Horizontal View:

Refresh page to view the preloader again

Code:

import com.Thumbnail.*;
var arr:Array = ["http://www.designscripting.com/wp-content/uploads/2008/11/thumb1.jpg"
    ,"http://www.designscripting.com/wp-content/uploads/2008/11/thumb2.jpg"
    ,"http://www.designscripting.com/wp-content/uploads/2008/11/thumb3.jpg"
    ,"http://www.designscripting.com/wp-content/uploads/2008/11/thumb4.jpg"   Â
    ,"http://www.designscripting.com/wp-content/uploads/2008/11/thumb5.jpg"]
var _thumbnail:ThumbnailManager = new ThumbnailManager(arr, ThumbnailManager.HORIZONTAL_ALIGN,100,100,10,0×000000 ,true)
addChild(_thumbnail);

Download Source Files

Feel free to edit and distrubute the code.

cheers