What do you want now? (Request extensions here)

Item Inspector does this. It shows what is called a leech table. This is a list of items you have problem with identified by a leech formula which measures the amount of trouble an item gives you. You can configure it to use other statistics like the number of times you get it wrong or the percentage of times you got it correct. But I recommend using the leech formula. It does a good job at measuring the trouble you have… (Disclosure: I am the author of Item Inspector)