Guys, this is something I adore giving at my classes I guess, deep down my students hate me for that. But I am a strong believer of the fact that without mastering modal verbs you can not even hope to understand the English language fully. Take a look, all the meaning of the modal verbs (can, have to, must, need, may, should, ought to) are presented in tables with illustrative examples and contemporary grammar rules. Hope you'll find it useful (for Intermediate - Advanced levels)
I guess, deep down my students hate me for that. But I am a strong believer of the fact that without mastering modal verbs you can not even hope to understand the English language fully. 