Favored Freeware: Skitch

Skitch is a refreshingly simple application that lets you easily resize your photos, jot down a quick sketch, take a lightning fast screen capture and share images online.

Pros: Skitch simplifies photo markup with a unique and intuitive interface. It’s great for adding visual directions to a map or pointing out objects of interest in a photo or screen capture. Once you’re done tweaking your photo, you can easily save it, email it, or upload it to your server, .Mac, Flickr or Skitch.com. Like Skitch, Skitch.com simplifies photo sharing with an intuitive layout which allows you to easily share, embed or display your photo almost anywhere with less clicks than it takes to read your email.

Cons: Skitch is currently available as a public beta and each beta release has a built-in expiration date. An updated version is always released before the current beta expires, but further updates may no longer be free once the application leaves the beta stage of its development.