Free Brushes

http://psbrushes.net/

A nicely designed site for all your brush needs

http://getbrushes.com/

A large collection of themed brushes. Examples include Halloween, music, desert, Africa, grunge, animals, thunder, Valentine's, space, cars, clouds and many others.

http://veredgf.fredfarm.com/vbrush/main.html

Older brush sets original designed for Photoshop 5-7 but should work in newer versions. Pattern brushes of different kinds.

http://www.echoica.net/brushes.php

Older brush sets original designed for Photoshop 5-7 but should work in newer versions. Butterfly, clouds, puzzle, geometric, grunge, ink, overlay, patterned, stars, wood, swirls etc.

http://cloud-no9-downloads-brushes.blogspot.com/

Summer, beach, hats, starfish, oranges and lemons, beer, floral

http://browse.deviantart.com/resources/applications/psbrushes/

Abstract, space, grunge, hair, lightning, anime, effects, grafitti, arabic, metal, women, trees, blood, skulls and bones, shadows, eyelashes and many more high quality sets.

http://www.photoshopsupport.com/tools/brushes.html#brushes-500ml

Large detailed list of brush sets

http://www.freephotoshop.com/html/free_brushes.html

Graphicxtras Brushes

http://www.adigitaldreamer.com/freephotoshopbrushes/

Holes, Woodgrains, stonework, toys, cracks

http://www.magurno.com/

Music, rap, bikes, deer, cartoon element brushes

http://inobscuro.com/brushes/

Swirly ornaments, lace, Paint strokes, Office tools, Numbers & bar codes, Postage stamps & postmarks, Dragonfly wings, Chinese symbols, Pixel glitter, Chains, Scrap & mask corners, Moth dance, Flowers, Gothique Decorations, Spider webs, Fibres, Rose garden, Pixels, Greek, Graffiti

http://www.alterform.com/content.php/Resources/Brushes

Lightning, flower and a few others.

http://www.yusuf-osman.com/tutorials/lightning/lightning.html

A cool lightning brush

http://www.adobe.com/cfusion/exchange/index.cfm#view=sn710&viewName=Photoshop%20Exchange&loc=en_us

Official Adobe website brush collection

http://www.ex-posed.com/brush/

A few random brushes

http://www.itsuji.net/brushes/index.php?x=setlist.php

Summer, chalk, fingerprints, drybrush, stripey, water, birds, Egypt, Leafy Green, windows icons, Wings of Paradise, She Sells Sea Shells , money, bubbles, lips, China, dirt specks and a few others

http://www.pixelchick.dk/pc.php?file=brushes

Grunge, signs, blurry, scratches

Make your own brush tutorial