Converting and resizing are surely the most common tasks you need to do with photos, so it's important to have a reliable app for the job.
John's Image Converter is a good choice, as it enables you to convert and resize single pictures or a whole directory of images. You can resize them either in pixels or percentage, and always making sure the original files are nor overwritten. But that's not all: with this program you can also create original photo collages in no time.
John's Image Converter features a tabbed interface where each tab is dedicated to the program's different functions: converting and resizing for one picture, for complete folders and collages. The first two ones are pretty straightforward. As for the latter, I must say I was a bit disappointed. The collage feature does include some interesting options, but the result wasn't as good as I expected: you can't preview the final result, there's no possibility to rearrange pictures once it's done and if your thumbnails are too big, they won't fit in it.
With John's Image Converter you can quickly resize and convert your photos, with the possibility to create a simple collage with them.