1. GIMP
GIMP is often called ‘the free Photoshop‘. Some of its features are customizable interface, photo enhancement, digital retouching.
GIMP works under Linux, Microsoft Windows (XP, Vista), Mac OS X, Sun OpenSolaris and FreeBSD.

2. Paint.NET

Paint.NET is free photoshop alternative. It is free image and photo editing software for computers that run Windows.

3. Inkscape
Inkscape is an Adobe Illustrator alternative. It is an open source vector graphics editor using the W3C standard Scalable Vector Graphics (SVG) file format. It works under Mac OS X and Windows.

4. FlashDevelop
Maybe the best free adobe flash alternative. It works under Windows XP, Windows Vista, Windows 7 and Mac OS X/Linux compatible using virtualization software.

Next two suggestions are two web based application that could help you, too.

5. splashup

Splashup is a powerful editing tool and photo manager.

6. picnik
Another web-based application that makes your photos fabulous with easy to use yet powerful editing tools.

I hope you’ve found some useful free adobe alternative in the examples above. If you know another free adobe alternative, I’ll be very thankful to post a comment with information about it and I’ll include its info to the list.