We had talked on ample of tools which allows you to reduce image sizes and help you in loading your web pages faster than ever. This tools strip out extra meta data and unwanted layers which reduces the size without loosing quality of the image. We discussed around 5 tools which you can read here.
Today we found another tools called as Puny PNG which uses a dirty transparency trick to remove additional layers which are useless.
Using the service is pretty is very simple. You can use the service to upload all the files and then download all of them as one zip files.
You can use this service to reduce file size to greater extent, specially very large image files. Check out Puny PNG