Actually there is dynamic hair at Renderosity.

Dixie Dynamic Hair,V4,A4,A3,Miki2,Laura, ETC.
http://www.renderosity.com/mod/bcs/index.php?ViewProduct=66228&keyword=dynamic&list=title

There is a Dynamic Hair catagory in the Free Stuff section here at Renderosity.

At Content Paradise ther is a Dynamic Hair Shaders product to color dynamic hair.
http://www.contentparadise.com/productDetails.aspx?id=2946

From RDMA, DNA P5 Pre-Raphaelite Hair,
http://www.runtimedna.com/DNA-P5-Pre-Raphaelite-Hair.html

DNA P5 Analinde Dynamic Hair for Victoria,
http://www.runtimedna.com/DNA-P5-Analinde-Dynamic-Hair-for-Victoria.html

DNA P5 Naughty Nikki Hair For Victoria,
http://www.runtimedna.com/DNA-P5-Naughty-Nikki-Hair-For-Victoria.html

DNA P5 Dynamic Hair Mega Pack,
http://www.runtimedna.com/DNA-P5-Dynamic-Hair-Mega-Pack.html

DNA P5 Fashion Hair for V2/V3,
http://www.runtimedna.com/DNA-P5-Fashion-Hair-for-V2-V3.html

DNA P5 Razor Hair for V2/V3,
http://www.runtimedna.com/DNA-P5-Razor-Hair-for-V2-V3.html

DNA P5 Romantic Hair for V2/V3,
http://www.runtimedna.com/DNA-P5-Romantic-Hair-for-V2-V3.html

Art Of Aesia vol6 A - Sexy Outfit,
http://www.runtimedna.com/Art-Of-Aesia-vol6-A-Sexy-Outfit.html

And for men, DNA P5 Dynamic Wizard Hair and Beard,
http://www.runtimedna.com/DNA-P5-Dynamic-Wizard-Hair-and-Beard.html

I may have missed some at these sites. Maybe, with encouragement, someone will put the effort into making some more dynamic hair.

LMK

Probably edited for spelling, grammer, punctuation, or typos.