Batch Image Converter does pretty much what you would expect it to - it will convert batches of images, changing format and resizing and, if necessary, deleting the original so as not to needlessly take up space.
Batch Image Converter is very simple - just a single interface with drop down "advanced" section. You choose your destination file parameters - JPG, PNG, TIFF, BMP or GIF - and one of Batch Image Converter's six size settings, including email and custom.
You can then drag and drop your photos into Batch Image Converter. The conversion takes place immediately, and you can view a log of the process if you want. Underneath the advanced options, you'll be able to specify where you want Batch Image Converter to save the new files - if you don't, they'll be mixed in with the originals.
Batch Image Converter is pretty simple, but for uncomplicated conversions, it's perfect.