I'm a huge fan of ImageWell. In fact, I've used it to edit nearly every image I've posted to TUAW. If you're unfamiliar, it's a quick-and-dirty image editor that's perfect when Photoshop would be overkill. Crop or resize your image, add a watermark or upload to your server easily.
Today, version 3.2 is available, and offers Flickr, SmugMug and ImageShack compatibility. Just click to send your image on its way. You can also annotate images with text, flip, rotate and more. Plus, ImageWell offers support for FTP, .Mac, SFTP and WebDAV. You can even designate a local folder for export.
ImageWell is free. However, you can purchase the "Xtras pack" - which offers features in addition to those mentioned here - for $14.95US.