Store files in the cloud.
Craft Pro can connect to Amazon S3, Rackspace Cloud Files, and Google Cloud Storage. When you set up a cloud-based asset source, it shows up right alongside your local sources, and you can even move folders and files between your local and cloud-based sources.
Keep your image sizes in check with transforms.
Whenever you need to output images at a certain size, you can create a new transform that sets the parameters. All of your transforms are available to all of your images, and the transformed images are created on demand.