To take things further than screengrab shortcuts allow, check out these five great OS X screengrab apps:
1. Grab (free with Mac OS X)
Bundled with Mac OS X, Apple's Grab is simple, but still provides features over and above system-wide shortcuts, including timed grabs and optional pointer types. It also omits drop shadows from grabs without the need for a Terminal hack.
2. Snapz Pro X ($29 for stills; $69 adds movies)
A long-time pro-level favourite with Mac users, Snapz Pro X offers significantly more options than Grab when taking screengrabs.
3. Layers ($24.95)
Newcomer Layers saves grabs as layered Photoshop PSD files, with each screen component saved to its own layer.
4. LittleSnapper ($39)
Primarily intended for website grabs, LittleSnapper also acts as an iPhoto-like repository for storing and browsing screengrabs.
5. SnapNDrag (free)
It lacks the features of the previous three apps, but SnapNDrag also lacks a price tag, yet offers more options than Apple's Grab.