There are many softwares which come exclusively for the task of creating thumbnails of images. One of the established commercial solutions for Windows that come to my mind is ThumbsPlus which comes with a 30 day evaluation period after which you will have to buy a license.
Mostly whenever I need to quickly create a lot of thumbnails I do that with the unbeaten light and immensely versatile freeware (for non-commercial usage) tool IrfanView.
For thumbnails we are able to define the size as well as several options for output:
- create single thumbnail images from selected files
- create a contact sheet of variable dimension
- create a HTML page with thumbnails of selected files
To do so we open the separate IrfanView Thumbnails program (or start it from the main application window on the menu entry File > Thumbnails):