Well I think in the free ones, there are not many which provide topic wise questions.
You can try
Niko's Blog Topic wise questions Santis 1.4 list of free mock exams this link has a list of 16
java question banks. these are also good.
irix exam topic wise but I am afraid it doesn't have IO related topic wise questions.
[ November 04, 2008: Message edited by: Ankit Garg ]