I'd like to learn about individualist anarchism. Do you know a free online resource for this? Who are contemporary philosophers working on this subject? Is there an online forum for individualists?
As a person, who studied anarchism a bit, i can assure you there's nothing wrong to start from Wikipedia page on individualist anarchism.
The early individual anarchists were Max Stirner and Benjamin Tucker. I recommend Stirner's The Ego and Its Own, it's an easy read and proved way more interesting than Nietzsche or Ayn Rand. Proudhon is also a major inspiration for individualist anarchism for his accounts on market economy.
Today individualist anarchists arguably developed into 3 currents: Neo-mutualism (advocated by the likes of Kevin Carson), agorism and so-called anarcho-capitalism. Communist anarchists reject the last branch, and Konkin also critiqued Rothbard.