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
http://www.corel.com/servlet/Satellite/us/en/Product/1166553885783#tabview=tab0

AutoDesk Sketch Book Pro
http://usa.autodesk.com/adsk/servlet/pc/index?id=6848332&siteID=123112

AutoDesk Sketch Book Mobile-for iPod touch and iPhone
http://usa.autodesk.com/adsk/servlet/pc/item?siteID=123112&id=13872203

Studio Artist 3.5 - Mac only -has some crazy autographing features
http://www.synthetik.com/

Corel Painter Essentials 4 - simplified/limited version of Painter
http://www.corel.com/servlet/Satellite/us/en/Product/1190317151777#tabview=tab0

Free NATURAL MEDIA/PAINT applications

My Paint- available for Linux and PC
http://mypaint.intilinux.com

Artweaver- Windows only- supports graphic tablets. Seems very similar to Painter
http://www.artweaver.de/overview-en/

Art Rage 2.5

http://www.ambientdesign.com/

Pixarra Twisted Brush- Windows only - Free and

http://www.pixarra.com/

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

http://www.koffice.org/krita/

Smooth Draw - very simple drawing program for Windows only

http://www.smoothdraw.com/product/index.htm

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 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