riously? Taxes != charity, regardless of what miniscule percentage of them might go to public programs. If you haven't put in the legwork and raised the money that he has, then you have zero room to criticise.
If you haven't researched Bono's business actions in detail, (facts) and don't know the feelings of many of his countrymen about said actions, then you are free to idolize him. Since much charity is tax deductable and some taxes are used for the greater good, in many cases, taxes can be considered charity.
If you really want to examine facts, there's a "wealth" of information "freely" available from Data.gov, which Steve links too. You might want to stay away from some of the long term economic data, it's quite disturbing to many people's world view. But there are a lot of data sets that are great for developing skills with.