go to Gutenberg.org it has thousands of public domain books for free download and reading as HTML pages. I'm sure it has the Koran (scripture of Islam) and the Bagavad-Gita (one of the most famous parts of the Hindu scriptures the Vedas).
For Islam, I recommend looking at works by Seyyed Hossein Nasr (philosophical) and Sheikh Fadhlalla Haeri (spiritual). Not sure about websites. I know that http://www.al-islam.org/ use to carry some of their works. Best to get the books.