Just a short list of icon designers I follow on twitter, I plan to collate this into a blog post eventually:

- Sofa: http://www.madebysofa.com/

- Pinvoke: http://twitter.com/pinvoke_com + http://www.pinvoke.com

- ByLine Break, Midtone Design: http://www.midtonedesign.com/ + http://twitter.com/DDrDark + http://twitter.com/bylinebreak + http://bylinebreak.com/

- Cocoia: http://twitter.com/Cocoia + http://www.icondesigner.net/

- Louis Harboe: http://twitter.com/spiralstairs + http://www.graphicpeel.com/

- Jonas Rask (retired): http://twitter.com/JonasRask + http://jonasraskdesign.com/

- Mathieu White: http://twitter.com/MathieuWhite + http://mathieuwhite.com/#funtime