N.S. Gill of Ancient/Classical History at About.com has an article on Mt. Vesuvius and Pompeii, with links to sites with photos.
Of interest is also the eye-witness account of Pliny the Younger, whose uncle Pliny the Elder was a casualty of the 79 CE erruption of the volcano.
(amended because prior URL's have disappeared)
Letters to Tacitus 6.16 & 6.20
6.16:
You ask me to write you something about the death of uncle so that the account you transmit to posterity is as reliable as possible. I am grateful to you, for I see that his death will be remembered forever if you treat it [sc. in your Histories]. He perished in a devastation of the loveliest of lands, in a memorable disaster shared by peoples and cities, but this will be a kind of eternal life for him. read on
6.20
You say that the letter I wrote for you about my uncle's death made you want to know about my fearful ordeal at Misenum (this was where I broke off). "The mind shudders to remember ... but here is the tale." read on
"Other Ancient Sources on Pompeii" has also disappeared wit Amherst College having re-designed its website.