Why digital painting? Digital painting allows you to create works in the same expressive way that painting does. I am not suggesting they are the same; however, I would encourage you to give it a try whether you are new to painting or are very proficient in the medium. One of the advantage of digital painting is the low (often free) price of entry. As long as you have a computer, you can use one of many free painting applications. In my experience, digital painting has encouraged many people to explore traditional painting.
There has also been a recent explosion of digital painting using handheld devices such as iPhones/iPod Touches and Nintendo DS gaming systems. Recently The New Yorker magazine featured an illustration painted using an iPhone on its cover. I have numerous links to this below.
Corel Painter is the granddaddy of digital painting applications. It is by far the most powerful and feature rich. It is a true natural media applicaion which is to say that it mimics how the media actually work. You can think of it as a painting simulator is you want. The software mimics the physics of each medium differently. Painting with watercolors is much different from painting with oil paints or acrylics. Plus, the colors of the paints blend in the same manner that real paint does. This in not true of Photoshop. Photoshop is often used for digital painting, but it is not a natural media application. Colors don't blend as real paints do nor do the colors have any of the qualities of natural media.
Painter is available for only $99 to students and faculty. Otherwise it is $399.

Here is a list of links to commercial (cost involved) and free natural media/painting programs that I have compiled over the years. Also included are a number of links to tutorials and related materials. I will try to sort them better as time allows. Have fun!

Commercial NATURAL MEDIA/PAINT applications

Corel Painter 11- THE NATURAL MEDIA/PAINT APPLICATION

AutoDesk Sketch Book Pro

AutoDesk Sketch Book Mobile-for iPod touch and iPhone

Studio Artist 3.5 - Mac only -has some crazy autographing features

Corel Painter Essentials 4 - simplified/limited version of Painter

Free NATURAL MEDIA/PAINT applications

My Paint- available for Linux and PC

Artweaver- Windows only- supports graphic tablets. Seems very similar to Painter

Art Rage 2.5 Starter Edition - very intuitive. A more featured version is available for a reasonable cost.

Pixarra Twisted Brush- Windows only - Free and

Krita-simple paint program available for Linux, Mac, and PC

Smooth Draw - very simple drawing program for Windows only

Painting applications for handheld devices and related articles

Jorge Colombo - he painted the cover illustration for the June 1, 2009 New Yorker on his iPhone

New Yorker article about Jorge's cover illustration featuring a video showing the process of the painting

LA Times article on Ed Velandria who using ArtRage and a tablet PC to paint quick portraits while riding the subway

Software tailored for Manga and Anime-can't vouch for it, don't know much about it

Deleter Software Comic Works

http://www.deleter.jp/eng/cw_english/

http://deleter-mangashop.com/goods.php?lang_id=en&goods_id=45&tsuka_conv=USD

http://my.smithmicro.com/win/graphics.html
http://my.smithmicro.com/mac/anime/index.html
http://my.smithmicro.com/mac/manga/index.html

Some of the artists here use this software
http://www.tokyopop.com/

Here is a link to a website of a magazine that I think many of you would like. www.imaginefx.com
Here is a direct link to numerous tutorials that are posted there:http://www.imaginefx.com/02287754330326480692/workshops.html

Figure drawing techniques
http://mos.futurenet.com/pdf/computerarts/CAP113_tut_bodies.pdf

Collection of 15 of the best ImagineFX tutorials
http://zero2illo.com/2009/04/15-of-the-best-imaginefx-digital-painting-tutorials/

Portfolio with some interesting digital paintings
http://ciaee-art.com/

3D people, here is a new Google 3D program with a free and commercial version. Supposed to be very easy to use. Haven't tried it yet. http://sketchup.google.com/

Overview of Free Painting Programs

http://www.techsupportalert.com/best-free-paint-program.htm

Corel tutorials on the use of Painter
http://www.corel.com/servlet/Satellite/us/en/Content/1171405215200

Tutorial on painting with Photoshop

http://www.melissaclifton.com/tutorial-freehand.html

Nice set of tutorials on painting with Photoshop

http://www.graphicmania.net/amazing-digital-painting-photoshop-tutorials/

Blending colors in Photoshop

http://www.digitalartform.com/archives/2005/04/painting_with_p.html

Corel Painter X/XI Links

Home page of one of the original Painter authors, numerous tutorials on using Painter
http://homepage.mac.com/pixlart/main.htm

Sign up for Corel Painter e-newsletter
http://apps.corel.com/painterx/us/community_newsletter.html

Overview of Painter, includes nice breakdown of different brushes
http://apps.corel.com/painterx/us/essence_new_features.html

Downloadable Training Movies
http://www.corel.com/servlet/Satellite/us/en/Content/1170190221936l

Corel tutorials on clone color
http://www.corel.com/servlet/Satellite/us/en/Content/1171405215200

Use filters to modify brush strokes, Surface Control>Quick Warp
http://www.designertoday.com/Tutorials/Painter/2057/Making.a.Mini.Poster.Corel.Painter.Tutorial.aspx

Numerous Tutorials here at the Designer Today website
http://www.designertoday.com/Tutorials/Painter/4.aspx

Pastel on Black Background
http://www.designertoday.com/Tutorials/Painter/1430/Pastel.on.Black.Background.Freehand.Sketch.Corel.Painter.Tutorial.aspx

Painting a Loose Style Portrait
http://www.designertoday.com/Tutorials/Painter/1826/Painting.a.Loose.Style.Portrait.Corel.Painter.Tutorial.aspx

Creating Abstract Art in Painter
http://www.designertoday.com/Tutorials/Painter/1855/Creating.Abstract.Art.Corel.Painter.Tutorial.aspx

Mixing Paint
http://www.designertoday.com/Tutorials/Painter/1887/Mixing.Colors.Corel.Painter.Tutorial.aspx

Corel Painter e-newsletter
http://apps.corel.com/painterx/us/community_newsletter.html

Watercolor effect
http://apps.corel.com/painterix/training/tutorial_watercolor.html

Impasto effect
http://graphicssoft.about.com/od/painter/ss/impasto.htm

Op Art- possibly use the movement of the image to make flag look moving even when still. Sense of movement symbolic of dynamic nature of humans?
http://www.julianstanczak.net/

Bridge Riley
http://www.webexhibits.org/colorart/riley.html
http://www.mishabittleston.com/artists/bridget_riley/

Digital Painting Links

How to paint an eye - simple tutorial and a simple looking result-nothing fancy
http://www.ehow.com/how_4691734_paint-brown-eyes-photoshop.html

How to paint an eye - involved, but very nice results
http://graphixworld.wordpress.com/2009/06/26/how-to-paint-a-human-eye-tutorial/

Some nice realistic brushes for Photoshop
http://doodle-lee-doo.deviantart.com/art/Real-Brush-Strokes-Set-122699209

How to paint a realistic eye
http://www.artsquared.co.uk/blog/2009/05/how-to-draw-a-realistic-eye/

http://www.cgsociety.org/

http://www.androidblues.com/JealousyStepbystep/jealousystep.html

http://www.3dluvr.com/content/section/9

http://www.henningludvigsen.com/

Pixel Brush - popular site for digital painting

http://www.pixelbrush.net/content/

http://www.3dm3.com/forum/articles.php?action=viewarticle&artid=101

Introduction to painting (fantasy art)

http://dianae.deviantart.com/art/Digital-Painting-Tutorial-74468761

Introductory tutorials

www.pxleyes.com has some good tutorials including this Incredibly detailed tutorial on how to draw a rose in PS

http://www.pxleyes.com/tutorial/photoshop/1467/How-To-Make-A-Digital-Painting-Of-A-Rose-From-Scratch.html