There’s a book coming out on the 100th anniversary of Ayn Rand’s birth (February 2, 1905) about the criticism her philosophy of Objectivism encountered over the years. The author, James Valliant, is perhaps the only person to undertake a comprehensive analysis of the Brandens’ biographies. It used to be online but has been recently taken down (coincidence? Hmm.).
[UPDATE (10/15/04): David Hayes also critiqued Barbara’s biography and it is still available online.]