PIXResizer is a simple app which does exactly what it says on the tin. Whilst there are a handful of resizing options available, including different output file types, it’s really simple resource to use. The program handily renames the exported file with the new resolution appended to the filename. PIXResizer also has the facility to batch resize image files.
PIXResizer is a freeware resource and is available for Windows only. The program can be downloaded here.