Image Resizer for Windows is a utility that lets you resize one or more selected image files directly from Windows Explorer by right-clicking. It’s handy and will always be something I install on any windows box I own. Works on Windows 8 too!

By default, image files with the following extensions can be resized: bmp, dib, gif, ico, jpe, jpeg, jpg, png, tif, tiff, wdp.

[Go to CodePlex site]