Strange Attractors
http://www.strangeattractors.com/

AClymer
http://www.andyclymer.com/

DutchType Library
http://www.dutchtypelibrary.nl/

Typotheque
http://www.typotheque.com/

Letterror
http://letterror.com

OurType
http://www.ourtype.be/

FontMaster
http://www.fontmaster.nl/

Superpolator
http://www.letterror.com/code/superpolator/

Nikola Djurek examples: http://www.letterror.com/code/superpolator/gallery.html

Robofab
http://www.letterror.com/code/robofab/

DrawBot
http://www.drawbot.com/

Frederik Berlaen

rounding UFO — great tool used in Tempera Rose

http://www.typemytype.com/

Tal TypeSupply
http://www.typesupply.com/