It's amazing how often you find you need to resize an image but if you only have something like Photoshop the process will be painfully slow when you're working with anything more than a few files. One of the fastest and easiest solutions for OS X is PhotoResize published by RootRise.
PhotoResize is a 64-bit app for OS X 10.6.6+ designed for both single file and batch operation and can handle JPG, JPEG2000, PSD, PNG, TIFF, BMP, GIF, ICNS, TGA, EXR, XMB, SGI, PNTG and RAW image types.
You can drag and drop files and folders onto the app as well as add them via a standard file dialog. You then select the required options (pre-sets are supported) which include the type of resizing (fit to rectangle, fit to height or width, crop to rectangle, and stretch to rectangle); the required image quality, the target height and width in percent, pixels, or size; the resolution; and whether the image should be resampled, up-scaled, and or sharpened.
You can also specify the default destination folder, which renaming scheme should be used such as keeping the original filename, adding to the filename, adding a prefix and or a suffix, and numbering the resized image.
Once everything is set up you can either resize the images one-by-one or have them all processed one after another. PhotoResize works amazingly quickly and for $1.99 it's a steal. PhotoResize gets a rating of 5 out of 5.