Rod Girle  Modal Logics and Philosophy Chapter 3
ModalTruth Table Applet [Single Line] [This is a new software 'widget' which is still under test.]
The next step is to relativize necessity and possibility to Access. You can experiment with this...
Roll your own [choose S5 or K]
Girle's Chapter 3 has a number of exercises. You can do them here (be sure to use the following logical symbols)
∼ & ∨ ⊃ ≡ ∀ ∃ ∴ □ ◊
[There are many other logics in Girle Chapter 3, send us an email if you would like them.]