For what concerns aptitude test, I don't know exactly what are u talking about. However, many (if not all) firms use SHL tests. Just go to www.shldirect.com and you will find tons of tests that are like the ones that u'll be given.
For interview prep, I will suggest you some books that may help you. Vault has some exceptional stuffs. IMHO, it very much depends on your background. If you are a brilliant and smart student, then u'll find these cases pretty easy. So take a look at some material, but don't expect to find any solution.