For those times when you need complete, uninterrupted concentration on a particular app you're working in, there is Doodim: a simple menubar utility that creates an Exposé-like dimming effect on the desktop and all background app windows. Doodim's product site offers a simple animated screenshot demo to help you see what really goes on, and users can even take the dimming effect all the way to black, so no nothing else is visible, save for the app you're working in. It's a slick idea and is done well, and toggling the dimming effect is simply handled from the menubar (the menubar, if you're wondering, is not dimmed). The site lists one known catch so far, which I personally haven't run into while playing with this: apparently, the dim effect can fail sometimes while switching between apps. Bouncing from Firefox to Mail, Adium, NetNewsWire, Safari and iTunes hasn't produced any issues for me yet though.

Doodim is provided free from La Chose Interactive, and I'm not sure if it's 10.4-only or not.

I'm beginning to think that today is some kind of image editing holiday, as Image Tricks, the freeware image editor that leverages Mac OS X Tiger's Core Image features, has been updated to version 2. New features include 'generators' - the ability to "randomly and manually generate images with mathematical algorithms," a fit-to-size option, PDF export, file size adjustment when exporting to JPEG, and other minor fixes and improvements.

Image Tricks has also been divided into Free and Pro versions. For a mere $9.95 the Pro version will give you six more generators than the free version, and BeLight software has stated they have more generators they can add from their todo list if enough customers show interest.

Check out BeLight Software's  Image Tricks product page for more details on its abilities, and the downloads page for a copy of the upgradable Free version.