FotoFlexer is a web based photo editing application its very simple to use, perfect for when your in need of resizing a photo and you don't have the nessersery desktop software its also free too which is always nice.
Here's a short video demonstration of FotoFlexer is action to upload a photo resize it and then save it.
Guide to uploading and resizing an image:
click upload photo
next click upload then select an image from your computer
wait for the upload to complete
select resize from the tools above your image
either select a preseet size or specify your own width the height will adjust accordingly then click apply
When finish click save at the top left then select the format either jpg or png the click save to my computer and your done.