You can find pretty much anything you'd need at http://www.gutenberg.net, as an English student it's my duty to know this.
Seriously though, don't use google for online texts, use Gutenberg, and if you can't find it there, it's not worth reading.
(or google for "title.txt")
For philosophic texts, uh, Republic is good, I'd also read Hegel and Kierkegaard as a way of understanding some more recent philosophy...
Plus I just plain love Kierkegaard...
Oh, and Spinoza, Ethics, is a nice one.
Thomas Aquinas too, but I've got to go, I'm missing my bus..