This website gives origins for many characters, as well as pictures of some earlier forms (e.g., from Oracle bones). Keep in mind that the structure of most characters is a phonetic and a semantic component put together (形声字). Most characters aren't pictograms (象形字), ideograms (指事字), or semantic combinations of other characters (会意字); although these types of characters have most captured the western imagination.
Also, etymology is a bit of a misnomer, as that would be for morphemes and words, not their graphical representation. It is, however, commonly called this.