From their website:

Standard Ebooks is a volunteer driven, not-for-profit project that produces new editions of public domain ebooks that are lovingly formatted, open source, and free.

I wanted to share this, because I think this is an awesome education resource for comrades, ebook enthusiasts, and just everyone!

And yes, they do have "The Communist Manifesto," but not any other Marxist literature that I know of. Feel free to contribute.