Yesterday I found a useful looking website about Chinese Etymology which shows variant forms of characters including Oracle Bone characters (甲骨文 jiăgŭwén), Bronze characters (金文 jīnwén) and Grass script characters (草書 căoshū). Some characters have many forms in the older versions of the Chinese script – up to 50 or so in some cases.
It also has information about the etymology and history of characters and written Chinese.
Another useful website I came across recently is a Chinese text annotation tool, which adds pop-up annotations containing pinyin transcriptions and English translations when you move your cursor over the characters in a Chinese text. The annotations can be applied to web pages or to Chinese texts pasted in the box on that site.